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The    Modern    Clock 


A  Study  of   Time  Keeping  Mechanism; 

Its   Construction,   Regulation 

and    Repair. 


BY   WARD    L.  GOODRICH 

Author  of  the  Watchmaker's   Lathe,  Its  Use  and  Abuse, 

BOSTON  COLLEGE  LIBRaKY 
OHJC8TNUT  HILL,  MASS. 


WITH   NUMEROUS   ILLUSTRATIONS   AND   DIAGRAMS 


CHICAGO 
Hazlitt  8c  Walker,   Publishers 
1905 


.^^n 


Copyrighted 

1905 

BY   HAZI.ITT   &   WALKER. 


CHAPTER  I. 

THE  NECESSITY  FOR    BETTER  SKILL  AMONG  CLOCKMAKERS 

The  need  for  information  of  an  exact  and  reliable  char- 
acter in  regard  to  the  hard  worked  and  much  abused  clock 
has,  we  presume,  been  felt  by  every  one  who  entered  the 
trade.  This  information  exists,  of  course,  but  it  is  scat- 
tered through  such  a  wide  range  of  pubHcations  and  is  found 
in  them  in  such  a  fragmentary  form  that  by  th^  time  a 
workman  is  sufficiently  acquainted  with  the  literature  of  the 
trade  to  know  where  to  look  for  such  information  he  no 
longer  feels  the  necessity  of  acquiring  it. 

The  continuous  decrease  in  the  prices  of  watches  and  the 
consequent  rapid  increase  in  their  use  has  caused  the  neglect 
of  the  pendulum  timekeepers  to  such  an  extent  that  good 
clock  men  are  very  scarce,  while  botches  are  universal. 
When  we  reflect  that  the  average  "life'  of  a  v/orker  at  the 
bench  is  rarely  mere  than  twenty  years,  we  can  readily  see 
that  information  by  verbal  instruction  is  rapidly  being  lost, 
as  each  apprentice  rushes  through  clock  work  as  hastily  as 
possible  in  order  to  do  watch  work  and  consequently  each 
"watchmaker"  knows  less  of  clocks  than  his  predecessor 
and  is  therefore  less  fitted  to  instruct  apprentices  in  his 
turn. 

The  striking  clock  will  always  continue  to  be  the  time- 
keeper of  the  household  and  we  are  still  dependent  upon  the 
compensating  pendulum,  in  conjunction  with  the  fixed  stars, 
for  the  basis  of  our  time-keeping  system,  upon  which  our 
commeicial  and  legal  calendars  and  the  movements  of  our 
ships  and  railroad  trains  depend,  so  that  an  accurate  knowl- 
edge of  its  construction  and  behavior  forms  the  essential 

3.  •.■    ..-..-:' 


4.  THE     MDDERN     CEOCK. 

basis  of  the  largest  part  of  our  business  and  social  system?, 
while  the  watches  for  which  it  is  slighted  are  themselves 
regulated , and  adjusted  at  the  factories  by  the  compensated 
pendulum. 

The  rapid  increase  in  the  dissemination  of  "standard 
time"*'  and  the  com.pulsory  use  of  watches  having  a  maxi- 
mum variation  of  five  seconds  a  week  by  railway  employes 
has  so  increased  the  standard  of  accuracy  dem.anded  by  the 
general  public  that  it  is  no  longer  possible  to  make  careless 
work  "go"  with  them,  and,  if  they  accept  it  at  all,  they 
are  apt  to  make  serious  deductions  from  their  estimate  of 
the  watchmaker's  skill  and  immediately  transfer  their  cus- 
tom to  some  one  who  is  more  thorough. 

The  apprentice,  when  he  first  gets  an  opportunity  to  ex- 
amine a  clock  movement,  usually  considers  it  a  very  myste- 
rious machine.  Later  on,  if  he  handles  many  clocks  of  the 
simple  order,  he  becomes  tolerably  familiar  with  the  time 
train ;  but  he  seldorn  becomes  confident  of  his  ability  regard- 
ing the  striking  part,  the  alarm  and  the  escapement,  chiefly 
because  the  employer  and  the  older  workmen  get  tired  of 
telling  him  the  same  things  repeatedly,  or  because  they  were 
similarly  treated  in  their  youth,  and  consider  clocks  a  nui- 
sance, any  how,  never  having  learned  clock  work  thorough- 
ly, and  therefore  being  unable  to  appreciate  it.  In  conse- 
quence of  such  treatment  the  boy  makes  a  few  spasmodic 
efforts  to  learn  the  portions  of  the  business  that  puzzle  him, 
and  then  gives  it  up,  and  thereafter  does  as  little  as  possible 
to  clocks,  but  begs  continually  to  be  put  on  watch  work. 

We  know  of  a  shop  where  two  and  sometimes  three 
workmen  (the  best  in  the  shop,  too)  are  constantly  employed 
upon  clocks  which  country  jewelers  have  failed  to  repair. 
If  clock  work  is  dull  they  will  go  upon  watch  work  (and 
they  do  good  work,  too),  but  they  enjoy  the  clocks  and  will 
do  them  in  preference  to  watches,  claiming  that  there  is 
greater  variety  and  more  interest  in  the  work  than  can  be 
found  in  fitting  factory  made  material  into  watches,  which 


TPIE     MODERN     CLOCK.  5 

consist  of  a  time  train  only.  Two  of  these  men  have  be- 
come famous,  and  are  frequently  sent  for  to  take  care  of 
complicated  clocks,  with  musical  and  mechanical  figure  at- 
tachments, tower,  chimes,  etc.  The  third  is  much  younger, 
but  is  rapidly  perfecting  himself,  and  is  already  competent 
to  rebuild  minute  repeaters  and  other  sorts  of  the  finer 
kinds  of  French  clocks.  He  now  totally  neglects  watch 
work,  saying  that  the  clocks  give  him  mort  money  and 
more  fun. 

We  are  confident  that  this  would  be  also  the  case  with 
many  another  American  youth  if  he  could  find  some  one 
to  patiently  instruct  him  in  the  few  indispensable  facts  which 
lie  at  the  bottom,  of  so  much  that  is  mysterious  and  from 
which  he  now  turns  in  disgust.  The  object  of  these  arti- 
cles is  to  explain  to  the  apprentice  the  mysteries  of  pendu- 
lums, escapements,  gearing  of  trains,  and  the  whole  tech- 
nical scheme  of  these  measurers  of  time,  in  such  a  way  that 
hereafter  he  may  be  able  to  answer  his  own  questions,  be- 
cause he  will  be  familiar  with  the  facts  on  which  they 
depend. 

Many  workmen  in  the  trade  are  already  incompetent  to 
teach  clockwork  to  anybody,  owing  to  the  slighting  process 
above  referred  to ;  and  the  frequent  demands  for  a  book  on 
clocks  have  therefore  induced  the  writer  to  undertake  its 
compilation.  Works  on  the  subject — nominally  so,  at  least 
— are  in  existence,  but  it  will  generally  be  found  on  exami- 
nation that  they  are  written  by  outsiders,  not  by  workmen, 
and  that  they  treat  the  subject  historically,  or  from  the 
standpoint  of  the  artistic  or  the  curious.  Any  information 
regarding  the  mechanical  movements  is  fragm.entary,  if 
found  in  them  at  all,  and  they  are  better  fitted  for  the  amuse- 
ment of  the  general  public  than  for  the  youth  or  man  who 
wants  to  know  "how  and  why."  These  facts  have  im- 
pelled the  writer  to  ignore  history  and  art  in  considering 
the  subject;  to  treat  the  clock  as  an  existing  mechanism 
which  must  be  understood  and  made  to  perform  its  func- 


THE     MODERN     CLOCK. 


tions  correctly ;  and  to  consider  cases  merely  as  housings 
of  mechanism,  regardless  of  how  beautiful,  strange  or  com- 
monplace those  housings  may  be. 

We  have  used  the  word  "compile"  advisedly.  The  writer 
has  no  new  ideas  or  theories  to  put  forth,  for  the  reason 
that  the  mechanism  we  are  considering  has  during  the  last 
six  hundred  years  had  its  mathematics  reduced  to  an  exact 
science;  its  variable  factors  of  material  and  mechanical 
movements  developed  according  to  the  laws  of  geometry  and 
trigonometry ;  its  defects  observed  and  pointed  out ;  its  per- 
formances checked  and  recorded.  To  gather  these  facts, 
illustrate  and  explain  them,  arrange  them  in  their  proper 
order,  and  point  out  their  relative  importance  in  the  whole 
sum  of  what  we  call  a  clock,  is  therefore  all  that  will  be  at- 
tempted. In  doing  this  free  use  has  been  made  of  the  ob- 
servations of  Saunier,  Reid,  Glasgow,  Ferguson,  Britten, 
Riefler  and  others  in  Europe  and  of  Jerome,  Playtner,  Finn, 
Learned,  Ferson,  Howard  and  various  other  Americans. 
The  work  is  therefore  presented  as  a  compilation,  which  it 
is  hoped  will  be  of  service  in  the  trade. 

In  thus  studying  the  modern  American  clocks,  we  use  the 
word  American  in  the  sense  of  ownership  rather  than  origin, 
the  clocks  which  come  to  the  American  workmen  to-day 
have  been  made  in  Germany,  France,  England  and  America. 

The  German  clocks  are  generally  those  of  the  Schwartz- 
wald  (or  Black  Forest)  district,  and  differ  from  others  in 
their  structure,  chiefly  in  the  following  particulars:  The 
movement  is  supported  by  a  horizontal  seat-board  in  the 
upper  portion  of  the  case.  The  wooden  trains  of  many  of 
the  older  type  instead  of  being  supported  by  plates  are  held 
in  position  by  pillars,  and  these  pillars  are  held  in  position 
by  top  and  bottom  boards.  In  the  better  class  of  wooden 
clocks  the  pivot  holes  in  the  pillars  are  bushed  with  brass 
tubing,  while  the  movement  has  a  brass  *scape  wheel,  steel 
wire  pivots  and  lantern  pinions  of  wood,  with  steel  trun- 


THE     MODERN     CLOCK.  7 

dies.  In  all  these  clocks  the  front  pillars  are  friction  tight, 
and  are  the  ones  to  be  removed  when  taking  down  the 
trains.  Both  these  and  the  modern  Swartzwald  brass  move- 
ments use  a  sprocket  wheel  and  chain  for  the  weights  and 
have  exposed  pendulums  and  weights. 

The  French  clocks  are  of  two  classes,  pendules  and  car- 
riage clocks,  and  both  are  liable  to  develop  more  hidden 
crankiness  and  apparently  causeless  refusals  to  go  than, 
ever  occurred  to  all  the  English,  German  and  American 
clocks  ever  put  together.  There  are  many  causes  for  this^ 
and  unless  a  mxan  is  very  new  at  the  business  he  can  tell 
stories  of  perversity,  that  w^ould  make  a  timid  apprentice 
want  to  quit.  Yet  the  French  clocks,  when  they  do  go,  are 
excellent  time-keepers,  finely  finished,  and  so  artistically  de- 
signed that  they  make  their  neighbors  seem  very  clumsy  by 
comparison.  They  are  found  in  great  variety,  time,  half- 
hour  and  quarter-hour  strike,  musical  and  repeating  clocks 
being  a  few  of  the  general  varieties.  The  pendulums  are 
very  short,  to  accommodate  themselves  to  the  artistic  needs 
of  the  cases,  and  nearly  all  have  the  snail  strike  instead  of 
the  count  wheel.  The  carriage  clocks  have  v/atch  escape- 
ments of  cylinder  or  lever  form,  and  the  escapement  is  fre- 
quently turned  at  right  angle  by  means  of  bevel  gears,  or 
contrate  wheel  and  pinion,  and  placed  on  top  of  the  move- 
ment. 

The  English  clocks  found  in  America  are  generally  of 
the  ''Hall"  variety,  having  heavy,  well  finished  movements, 
with  seconds  pendulum  and  frequently  with  calendar  and 
chime  movements.  They,  like  the  German,  are  generally 
fitted  with  weights  instead  of  springs.  There  are  a  few 
English  carriage  clocks,  fitted  with  springs  and  fuzees, 
though  most  of  them,  like  the  French,  have  springs  fitted  in 
going  barrels. 

The  American  clocks,  with  which  the  apprentice  will  nat- 
urally have  most  to  do,  may  be  roughly  divided  into  time. 


8  THE     MODERN     CLOCK. 

time  alarm,  tim.e  strike,  time  strike  alarm,  time  calendar 
and  electric  winding.  The  American  factories  generally 
each  make  about  forty  sizes  and  styles  of  movements,  and 
case  them  in  many  hundreds  of  different  ways,  so  that  the 
workman  will  frequently  find  the  same  movement  in  a  large 
number  of  clocks,  and  he  will  soon  be  able  to  determine  from 
the  characteristics  of  the  movement  what  factory  made  the 
clock,  and  thus  be  able  to  at  once  turn  to  the  proper  cata- 
logue if  the  name  of  the  maker  be  erased,  as  frequently 
happens. 

This  comparative  study  of  the  practice  of  different  facto- 
ries will  prove  very  interesting,  as  the  movement  comes  to 
the  student  after  a  period  of  prolonged  and  generally  se- 
vere use,  which  is  calculated  to  bring  out  any  existing  de- 
fects in  construction  or  workmanship ;  and  having  all  makes 
of  clocks  constantly  passing  through  his  hands,  each  ex- 
hibiting a  characteristic  defect  more  frequently  than  any 
other,  he  is  in  a  much  better  position  to  ascertain  the  merits 
and  defects  of  each  maker  than  he  v/ould  be  in  any  factory. 

Having  thus  briefly  outlined  the  kinds  of  machinery  used 
in  measuring  time,  we  will  now  turn  our  attention  to  the 
examination  of  the  theoretical  and  mechanical  construction 
of  the  various  parts. 

The  man  who  starts  out  to  design  and  build  a  clock  will 
find  himself  limited  -  in  three  particulars :  It  must  run  a 
specified  time;  the  arbor  carrying  the  minute  hand  must 
turn  once  in  each  hour ;.  the  pendulum  must  be  short  enough 
to  go  in  the  case.  Two  of  these  particulars  are  changeable 
according  to  circumstances ;  the  length  of  time  run  may  be 
thirty  hours,  eight,  thirty,  sixty  or  ninety  days.  The  pendu- 
lum may  be  anywhere  from  four  inches  to  fourteen  feet,  and 
the  shorter  it  is  the  faster  it  will  go.  The  one  definite 
point  in  the  time  train  is  that  the  minute  hand  must  turn 
once  in  each  hour.  We  build  or  alter  our  train  from  this 
point  both   ways,   back   through    changeable    intermediate 


THE     MODERN     CLOCK. 


wheels  and  pinions  to  the  spring  or  weight  forming  the 
source  of  power,  and  forward  from  it  through  another 
changeable  series  of  wheels  and  pinions  to  the  pendulum. 
Now  as  the  pendulum  governs  the  rate  of  the  clock  we  will 
commence  with  that  and  consider  it  independently. 


CHAPTER  II. 

'  THE    NATURAL    LAWS    GOVERNING    PENDULUMS. 

Length  of  Pendulum. — A  pendulum  is  a  falling  body 
and  as  such  is  subject  to  the  laws  which  govern  falling  bod- 
ies. This  statement  may  not  be  clear  at  first,  as  the  pendu' 
lum  generally  moves  through  such  a  small  arc  that  it  does 
not  appear  to  be  falling.  Yet  if  we  take  a  pendulum  and 
raise  the  ball  by  swinging  it  up  tmtil  the  ball  is  level  with  the 
point  of  suspension,  as  in  Fig.   i,  and  then  let  it  go,  we 


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^-^ 

Fig.  1.    Dotted  lines  show  path  of  pendulum. 

shall  see  it  fall  rapidly  until  it  reaches  its  lowest  point,  and 
then  rise  until  it  exhausts  the  momentum  it  acquired  in  fall- 
ing, when  it  will  again  fall  and  rise  again  on  the  other  side ; 
this  process  will  be  repeated  through  constantly  smaller 
arcs  until  the  resistance  of  the  air  and  that  of  the  pendulum 
spring  shall  overcome  the  other  forces  which  operate  to 
keep  it  in  motion  and  it  finally  assumes  a  position  of  rest 
at  the  lowest  point  (nearest  the  earth)  which  the  pendulum 

ID 


THE     MODERN     CLOCK.  II 

rod  will  allow  it  to  assume.  When  it  stops,  it  will  be  in 
line  between  the  center  of  the  earth  (center  of  gravity) 
and  the  fixed  point  from  which  it  is  suspended.  True,  the 
pendulum  bob,  when  it  falls,  falls  under  control  of  the 
pendulum  rod  and  has  its  actions  modified  by  the  rod ;  but 
it  falls  just  the  same,  no  matter  how  small  its  arc  of  motion 
may  be,  and  it  is  this  influence  of  gravity — that  force  which 
makes  any  free  body  move  toward  the  earth's  center — 
which  keeps  the  pendulum  constantly  returning  to  its  low- 
est point  and  which  governs  very  largely  the  time  taken  in 
moving.  Hence,  in  estimating  the  length  of  a  pendulum, 
we  must  consider  gravity  as  being  the  prime  mover  of  our 
pendulum. 

The  next  forces  to  consider  are  mass  and  weight,  which, 
when  put  in  motion,  tend  to  continue  that  motion  indefinitely 
unless  brought  to  rest  by  other  forces  opposing  it.  This  is 
known  as  momentum.  A  heavy  bob  will  swing  longer 
than  a  light  one,  because  the  momentum  stored  up  during 
its  fall  will  be  greater  in  proportion  to  the  resistance  which 
it  encounters  from  the  air  and  the  suspension  spring. 

As  the  length  of  the  rod  governs  the  distance  through 
which  our  bob  is  allowed  to  fall,  and  also  controls  the  direc- 
tion of  its  motion,  we  must  consider  this  motion.  Refer- 
ring again  to  Fig.  i,  we  see  that  the  bob  moves  along  the 
circumference  of  a  circle,  with  the  rod  acting  as  the  radius 
of  that  circle ;  this  opens  up  another  series  of  facts.  The 
circumference  of  a  circle  equals  3.1416  times  its  diameter, 
and  the  radius  is  half  the  diameter  (the  radius  in  this  case 
being  the  pendulum  rod).  The  areas  of  circles  are  propor- 
tional to  the  squares  of  their  diameters  and  the  circumfer- 
ences are  also  proportional  to  their  areas.  Hence,  the 
lengths  of  the  paths  of  bobs  moving  along  these  circumfer- 
ences are  in  proportion  to  the  squares  of  the  lengths  of  the 
pendulum  rods.  This  is  why  -a  pendulum  of  half  the  length 
will  oscillate  four  times  as  fast. 

Now  we  will  apply  these  figures  to  our  pendulum.     A 


12  THE     MODERN     CLOCK. 

body  falling  in  vacuo,  in  London,  moves  32.2  feet  in  one 
second.  This  distance  Kas  by  common  consent  among 
mathematicians  been  designated  as  g.  The  circumference 
of  a  circle  equals  3.416  times  its  diameter.  This  is  repre- 
sented as  77-  Now,  if  we  call  the  time  t,  we  shall  have  the 
formula : 


'Vi 


^ 


Substituting  the  time,  one  second,  for  t,  and  doing  the  same 
with  the  others,  we  shall. have: 

CJ2.2    ft.  r     ^      r 

I  =  — ^^=  c>.26i6  feet. 

(3.i4i6)»      ^ 

Turning  this  into  its  equivalent  in  inches  by  multi- 
plying by  12,  we  shall  have  39.1393  inches  as  the  length  of 
a  one-second  pendulum  at  London. 

Now,  as  the  force  of  gravity  varies  somewhat  with  its 
distance  from  the  center  of  the  earth,  we  shall  find  the  value 
of  g  in  the  above  formula  varying  slightly,  and  this  will 
give  us  slightly  different  lengths  of  pendulum  at  different 
places.    These  values  have  been  found  to  be  as  follows : 

Inches. 

The  Equator  is 3g 

Rio   dc  Janiero 39-01 

Madras 3(;'.02 

New  York , 39. 10x2 

Paris 39.13 

London  39-14 

Edinbv.rsh 39.15 

Greenland 39-20 

North  and  South  Pole 39.206 

Now,  taking  another  look  at  our  formula,  we  shall  see 
that  we  may  get  the  length  of  any  pendulum  by  multiply- 
n^^TT  (which  is  3.1416)  by  the  square  of  the  time  required: 
To  find  the  length  of  a  pendulum  to  beat  three  seconds : 

3' =  9-     39-1393x9  =  352.2537  inches  =  29.3544  feet. 
A  pendulum  beating  two-thirds  of  a  second,  or  90  beats: 


THE     MODERN     CLOCK.  I3 

(2).  ^  4.    .39-1393     X    4^  17.3953  inches. 
A  pendulum  beating  half-seconds  or  120  beats : 
(,^,^,.39-.393X.^^_^3^S  inches. 

Center  of  Oscillation. — Having  now  briefly  consid- 
ered the  basing  facts  governing  the  time  of  oscillation  of 
the  pendulum,  let  us  examine  it  still  further.  The  pendu- 
lum shown  in  Fig.  i  has  all  its  weight  in  a  mass  at  its  end, 
but  we  cannot  make  a  pendulum  that  way  to  run  a  clock, 
because  of  physical  limitations.  We  shall  have  to  use  a 
rod  stiff  enough  to  transmit  power  from  the  clock  move- 
ment to  the  pendulum  bob  and  that  rod  will  weigh  some- 
thing. If  we  use  a  compensated  rod,  so  as  to  keep  it  the 
same  length  in  varying  temperature,  it  may  weigh  a  good 
deal  in  proportion  to  the  bob.  How  will  this  affect  the  pen- 
dulum ? 

If  we  suspend  a  rod  from  its  upper  end  and  place  along- 
side of  it  our  ideal  pendulum,  as  in  Fig.  2,  we  shall  find  that 
they  will  not  vibrate  in  equal  times  if  they  are  of  equal 
lengths.  Why  not?  Because  when  the  rod  is  swinging 
(being  stiff)  a  part  of  its  weight  rests  upon  the  fixed  point 
of  suspension  and  that  part  of  the  rod  is  consequently  not 
entirely  subject  to  the  force  of  gravity.  Now,  as  the  time 
in  which  our  pendulum  will  swing  depends  upon  the  dis- 
tance of  the  effective  center  of  its  mass  from  the  point  of 
suspension,  and  as,  owing  to  the  difference  in  construction, 
the  center  of  mass  of  one  of  our  pendulums  is  at  the  center 
of  its  ball,  while  that  of  the  other  is  somewhere  along  the 
rod,  they  will  naturally  swing  in  different  times. 

Our  other  pendulum  (the  rod)  is  of  the  same  size  all  the 
way  up  and  the  center  of  its  effective  mass  would  be  the 
center  of  its  weight  (gravity)  if  it  were  not  for  the  fact 
which  we  stated  a  moment  ago  that  part  of  the  weight  is 
upheld  and  rendered  ineft'ective  by  the  fixed  support  of  the 


H 


THE     MODERN     CLOCK. 


f-A- 


6 


A^ 


0 


a 


Fig.  2.    Two  pendulums  of  equal  length  but  unequal  vibration.    B,  cen- 
ter of  oscillation  for  both  pendulums. 


y     ^ 
•     y 

y     y 

y    y 


?s 


Fig.  3. 


THE     MODERN     CLOCK. 


^5 


pendulum  rod,  all  the  while  the  pendulum  is  not  in  a  vertical 
position.  If  we  support  the  rod  in  a  horizontal  position^  as 
in  Fig.  3,  by  holding  up  the  lower  end,  the  point  of  sus- 
pension, A,  will  support  half  the  weight  of  the  rod ;  if  we 
hold  it  at  45  degrees  the  point  of  suspension  will  hold  less 
than  half  the  weight  of  the  rod  and  more  of  the  rod  will 
be  affected  by  gravity;  and  so  on  down  until  we  reach  the 
vertical  or  up  and  down  position.  Thus  we  see  that  the 
force  of.  gravity  pulling  on  our  pendulum  varies  in  its  ef- 
fects according  to  the  position  of  the  rod  and  consequently 
the  effective  center  of  its  mass  also  varies  with  its  position 
and  we  can  only  calculate  what  this  mean  (or  average)  po- 
sition is  by  a  long  series  of  calculations  and  then  taking  an 
average  of  these  results. 

We  shall  find  it  simpler  to  measure  the  time  of  swing  of 
the  rod  which  we  will  do  by  shortening  our  ball  and  cord 
until  it  will  swing  in  the  same  time  as  the  rod.  This  will  be 
at  about  two-thirds  of  the  length  of  the  rod,  so  that  the 
effective  length  of  our  rod  is  about  two-thirds  of  its  real 
length.  This  effective  length,  which  governs  the  time  of 
vibration,  is  called  the  theoretical  length  of  the  pendulum 
and  the  point  at  which  it  is  located  is  called  its  center  of 
oscillation.  The  distance  from  the  center  of  oscillation  to 
the  point  of  suspension  is  called  the  theoretical  length  of  the 
pendulum  and  is  always  the  distance  which  is  given  in  all 
tables  of  lengths  of  pendulums.  This  length  is  the  one 
given  for  two  reasons :  First,  because,  it  is  the  time-keeping 
length,  which  is  what  we  are  after,  and  second,  because,  as 
we  have  just  seen  in  Fig.  3,  the  real  length  of  the  pendulum 
increases  as  more  of  the  weight  of  the  instrument  is  put  into 
the  rod.  This  explains  why  the  heavy  gridiron  compensa- 
tion pendulum  beating  seconds  so  common  in  regulators  and 
which  measures  from.  56  to  60  inches  over  all,  beats  in  the 
same  time  as  the  wood  rod  and  lead  bob  measuring  45 
inches  over  all,  while  one  is  apparently  a  third  longer  than 
the  other. 


i6 


THE     MODERN     CLOCK. 


Table  Showing  the  Length  of  a  Simple  Pendulum 

That  performs  in  one  hour  any  given  number  of  oscillations,  from  r 
to  20,000,  and  the  variation  in  this  length  that  will  occasion  a  difference 
of  I  minute  in  24  hours. 

Calculated  by  E.  Gourdin. 


of 
rHolir. 

S2 

Pi 

p 

0  -■ 

^  s 

0     u 

„• 

Length 
te  in  24 
meters. 

.1 

1^1 

1' 

B   0 

u 

it 

%\ 

;5s 

H   0 

l.sl 

0.     -^ 

-:M 

0  '^ 

♦-1     r:: 

2  «  S 

3  -s 

y^      .-3 

.2  «- 

3  Z! 

A    .t: 

2«.S 

S 

ih 

%  J 

^ 

% 

|oi 

y-<  3. 

% 

|o| 

M 

cS  u  0 

m 

^  Ki  0 

0 

>.°s  ■ 

0 

>^S 

0 

>ex 

20,000 

32.2 

G.04 

13,200 

73.9 

0.10 

8,200 

191.5 

0.26 

19,000 

35.7 

0.05 

13,100 

75.1 

0.10 

8,100 

196.3 

0.27 

18,000 

39.8 

0.05 

13,000 

76.2 

0.10 

8,000 

201.3 

o.2r 

17,900 

40.2 

0.06 

12,900 

77.4 

0.11 

7,900 

206.4 

0.28 

17,800 

40.7 

0.06 

12,800 

78.6 

0.11 

7,800 

211.7 

0.29 

17,700 

41.1 

0.06 

12,700 

79.9 

0.11 

7,700 

217.3 

0.30 

17.fi00 

41.6 

0.06 

12,600 

81.1 

0.11 

7,600 

223.0 

0.3<> 

17.500 

42.1 

0.06 

12,5110 

82.4 

0.11 

7,500 

229.0 

0.31 

17,400 

42.4 

0.06 

12,400 

83.8 

0.11 

7,400 

235.2 

0.3* 

17,300 

43.0 

0.06 

12,300 

85.1 

0.12 

7,300 

241.7 

0.3* 

17,200 

43.5 

0.06 

12,200 

86.5 

0.12 

7,200 

248.5 

0.34 

17.100 

44.0 

0.06 

12,100 

88.0 

0.12 

7,100 

255.7 

0.3* 

17,000 

44.6 

0.06 

12,000 

89.5 

0.12 

7,000 

262.9 

0.3& 

16,900 

45.1 

0.06 

11,900 

91.0 

0.12 

6,900 

270.5 

o.sr 

16,800 

45.7 

0.06 

11,800 

92.5 

0.13 

6,800 

278.6 

0.3» 

16,700 

46.3 

0.06 

11,700 

94.1 

0.13 

6,700 

286.9 

0.S» 

16.600 

46.7 

0.07 

11,600 

95.7 

0.13 

6,600 

295.7 

0.40 

16,500 

47.3 

0.07 

11,500 

97.4 

0.13 

6,500 

304.9 

0.41 

16,400 

47.9 

0.07 

11,400 

99.1 

0.13 

6,400 

314.5 

0.4* 

16,300 

48.5 

0.07 

11,300 

100.9 

0.14 

6,300 

324.5 

0.44 

16,200 

49.1 

0.07 

11,2U0 

102.7 

0.14 

6,200 

335.1 

0.46 

16,100 

49.7 

0.07 

11,100 

104.5 

0.14 

6,100 

34R.2 

o.4r 

16,0<iO 

50.0 

0.07 

11,000 

106.5 

0.14 

6,C00 

357.8 

0.4* 

15,900 

51.0 

0.07 

10,900 

108.4 

0.15 

5,900 

370.0 

0.50 

15,800 

51.6 

0.07 

10,800 

110.5 

0.15 

5,800 

382.9 

0.5* 

15,7ti0 

52.3 

0.07 

10,700 

112.5 

0.15 

5,700 

396.4 

0.54 

15.600 

52.9 

0.07 

10,600 

114.6 

0.16 

5,600 

410.7 

0.50 

15,500 

53.6 

0.07 

10,500 

116.8 

0.16 

5,500 

425.^ 

0.58^ 

15,400 

54.3 

0.08 

10,400 

119.1 

0.16 

5,400 

440.1 

0.6O 

15,300 

55.0 

0.08 

11,300 

111.4 

0.17 

5,300 

458.5 

0.6* 

15,200 

55.7 

0.08 

10,200 

123.8 

0.17 

5,200 

476.3 

0.6S 

15,100 

56.5 

0.08 

10,100 

126.3 

0.17 

5,100 

495.2 

o.er 

15,000 

57.3 

0.08 

10,000 

128.8 

0.18 

5,000 

515.2 

0.70 

14,900 

58.0 

0.08 

9,900 

131.4 

0.18 

4,900 

536.5 

0.7* 

14,800 

58.8 

0.08 

9,800 

134.1 

0.18 

4,800 

559.1 

0.78 

14,700 

59.6 

0.08 

9,700 

136.9 

0-19 

4,700 

583.1 

0.70 

14,600 

60.4 

0.08 

9,600 

139.8 

0.19 

4,600 

•  608.7 

O.Si 

14,500 

61.3 

0.08 

9,500 

142.7 

0.19 

4,500 

636.1 

0.8R 

14,400 

68.1 

0.09 

9,400 

145.8 

0.20 

4,400 

665.3 

0.90 

141300 

63.0 

0.09 

9,300 

148.9 

0-20 

4,300 

696.7 

0.9S 

14,200 

63.9 

0.09 

9,200 

152.2 

0.21 

4,200 

730.2 

0.90 

14,100 

64.8 

0.09 

9,100 

155.5 

0-21 

4,100 

766.2 

1.04 

14,000 

65.7 

0.09 

9,noo 

159.0 

0.22 

4,000 

805.0 

1.00 

13,900 

66.7 

0.09 

8,900 

162.6 

0.22 

3,950 

825.5 

1.1* 

13,800 

67.6 

0.09 

8,800 

IK6.3 

0.23 

3,900 

846.8 

1.15 

13.700 

68-6 

0.(19 

8,700 

170.2 

0.2:3 

3,850 

869.0 

l.ld 

13,600 

69.6 

0.09 

8,600 

173.7 

0.24 

S,800 

892.0 

1.21 

13,500 

70.7 

0.09 

8,500 

178.3 

0.24 

3,750 

915.9 

1.2s 

13,400 

71.7 

0.10 

8,400 

182.5 

0.25 

3,700 

940.1 

L28 

13,300 

72.8 

0.10 

8,300 

187.0 

0.25 

3,650 

966.8 

1.31 

THE     MODERN     CLOCK. 

Table  of  the  Length  of  a  Simple  Pendulum, 

(continued.) 


CO 

§ 

■J 

j2 

To  Produce  in 
24  Hours 

1 

To  Produce 

in  24  Hours 

i: 

1    Minute. 

% 

1  M 

nute. 

1    3 

u 

Length 
in 

2« 

^i 

t^t 

<=  i 

si 

^%% 

A^ 

'°  'z 

Meters. 

Loss, 

Gain, 

^  " 

n 

o|  S 

%r^ 

1  "- 

Lengthen  by 

Shorten    by 

a 

3 

:a 

E 

3 

- 

Meters. 

Meters. 

"A 

^^ 

C/3S 

^ 

3  600 

0.9939 

1.38 

1.32 

1900 

3.5G8 

0.0950 

0.0048 

3,550 

1.0221 

1,42 

1.36 

1,800 

3  975 

0  0055 

0.0053 

3,500 

1.0515 

1.46 

1.40 

1,700 

4.457 

0.0062 

-0.0059 

3,450 

1.0822 

1.50 

144 

1;600 

5.031 

0  0070: 

0.00(^7 

3.400 

1.1143 

1.55 

1.48 

1,500 

5  725 

0.01^80 

0.0076 

3,350 

1.1477 

1.60 

1.53 

1,400 

6.572 

0.0091 

0.0087 

3,300 

1.1828 

1.64 

1.57 

1,300 

7.6-22 

0.0106 

0.0101 

3.250 

1.2194 

1.69 

1.62 

1,200 

8.945 

0  0124 

0.0119 

3,200 

1.2578 

175 

1.67 

1,100 

10.645 

0.0148 

0.0142 

3,150 

1.2981 

1.80 

1.73 

1,000 

12.880 

0.0179 

0.0171 

3,100 

1.3403 

1.86 

178 

900 

15  902 

0.0221 

0.0211 

3,050 

1.3846 

1.93 

1.84 

800 

20.126 

0  0280 

0.0268 

3,U00 

1.4312 

1.99 

190 

700 

26.287 

0  0365 

0.0350 

2.900 

1.5316 

2.13 

2.04 

600 

35  779 

00497 

0.0476 

2.800 

1.6429 

2.28 

218 

500 

51  521 

0.0716 

0.0685 

2.700 

1.7669 

2.46 

2  35 

400 

SO  502 

0.1119 

0.1071 

2,600 

19054 

2.65 

2  53 

30© 

143115 

0.1989 

0.1903 

2,500 

2.0609 

2  87 

2.74 

200 

322  008 

0.4476 

0.4282 

2,400 

2.2362 

3.11 

297 

100 

1,283.034 

1.7904 

1.7131 

2,800 

2.4349 

3.38 

3  24 

60 

3,577.871 

4  9732 

4.7586 

2,200 

2  6612 

3.70 

8.54 

50 

5,152.135 

7.1613 

6.8521 

2,100 

2.9207 

4.06 

3  88 

1 

12,880,337.930 

17,9036700 

17,130.8500 

2,000 

32201 

4.48 

4.28 

In  the  foregoing  tables  all  dimensions  are  given  in  meters 
and  millimeters.  If  it  is  desirable  to  express  them  in  feet 
and  inches,  the  necessary  conversion  can  be  at  once  effected 
in  any  given  case  by  employing  the  following  conversion 
table,  which  will  prove  of  considerable  value  to  the  watch- 
maker for  various  purposes : 


Ii  THE     MODERN     CLOCK. 

Conversioa  Table  of  Inches,  Millimeters  and  French  Lines. 


Inches  expressed  in 

MUlimeters 

expressed 

French  Lines  expressed 

Millimeters  and  French 

in  Inches  and  French 

in  Inches  and 

Lines. 

Lines. 

Millimeters. 

i 

Equal  to 

1 

Equal  to 

Equal  to 

u 

^ 

M 

Millimeters 

French 
Lines. 

S 

Inches. 

French 
Lines. 

fa 

Inches. 

Millimeters 

1 

25  39954 

11.25951 

1 

0.0393708 

0.44329 

1 

0.088414 

2.25583 

^ 

50.79908 

22.51903 

2 

0.0787416 

0.88659 

2 
8 

0.177628 
0266441 

4.51166 
6.76749 

3 

76.19862 

33.77854 

3 

0.1181124 

1.32989 

4 

0.355255 

9.02332 

4 

101.59816 

45.03806 

4 

0.1574832 

1.77318 

5 

0.444069 

11.27915 

5 

126.99771 

56.29757 

5 

0.1968539 

2.21648 

6 

0.532883 

13.53497 

6 

162.39725 

67.55709 

6 

0.2362247 

2.65978 

7 

0.621697 

15.79080 

7 

177.79679 

78  81660 

7 

0.2755955 

3.10307 

8 
9 

0.710510 
0.799324 

18.04663 
20.30246 

8 

203  19633 

90.07612 

8 

0.3149664 

3.54637 

10 

0.888138 

22.55829 

9 

22859587 

10133563 

9 

0.3543371 

3  98966 

11 

0.976952 

2481412 

10 

253.99541 

112.59515 

10 

0.3937079 

4.43296 

12 

1.065766  27.06995 

Center  of  Gravity. — The  watchmaker  is  concerned  only 
with  the  theoretical  or  timekeeping  lengths  of  pendulums, 
as  his  pendulum  comes  to  him  ready  for  use;  but  the  clock 
maker  who  has  to  build  the  pendulum  to  fit  not  only  the 
movement,  but  also  the  case,  needs  to  know  more  about  it, 
as  he  must  so  distribute  the  weight  along  its  length  thai  it 
may  be  given  a  length  of  6o  inches  or  of  44  inches,  or  any- 
thing between  them,  and  still  beat  seconds,  in  the  case  of  a 
regulator.  He  must  also  do  the  same  thing  in  other  clocks 
having  pendulums  which  beat  other  numbers  than  60. 
Therefore  he  must  know  the  center  of  his  weights ;  this  is 
called  the  center  of  gravity.     This  center  of  gravity  is  often 


THE     MODERN     CLOCK. 


19 


confused  by  many  with  the  center  of  oscillation  as  its  real 
purpose  is  not  understood.  It  is  simply  used  as  a  starting 
point  in  building  pendulums,  because  there  must  be  a  start- 
ing point,  and  this  point  is  chosen  because  it  is  always  pres- 
ent in  every  pendulum  and  it  is  convenient  to  work  both 
ways  from  the  center  of  weight  or  gravity.  In  Fig.  2  we 
have  two  pendulums,  in  one  of  which  (the  ball  and  string) 
the  center  of  gravity  is  the  center  of  the  ball  and  the  center 
of  oscillation  is  also  at  the  center  (practically)  of  the  ball. 
Such  a  pendulum  is  about  as  short  as  it  can  be  constructed 
for  any  given  number  of  oscillations.  The  other  (the  rod) 
has  its  center  of  gravity  manifestly  at  the  center  of  the  rod, 
as  the  rod  is  of  the  same  size  throughout ;  yet  we  found  by 
comparison  with  the  other  that  its  center  of  oscillation  was 
at  two-thirds  the  length  of  the  rod,  measured  from  the  point 
of  suspension,  and  the  real  length  of  the  pendulum  was  con- 
sequently one-half  longer  than  its  time  keeping  length,  which 
is  at  the  center  of  oscillation.  This  is  farther  apart  than 
the  center  of  gravity  and  oscillation  will  ever  get  in  actual 
practice,  the  most  extreme  distance  in  practice  being  that 
of  the  gridiron  pendulum  previously  mentioned.  The  cen- 
ter of  gravity  of  a  pendulum  is  found  at  that  point  at  which 
the  pendulum  can  be  balanced  horizontally  on  a  knife  edge 
and  is  marked  to  measure  from  when  cutting  off  the  rod. 

The  center  of  oscillation  of  a  compound  pendulum  must 
always  be  below  its  center  of  gravity  an  amount  depending 
upon  the  proportions  of  weight  between  the  rod  and  the  bob. 
Where  the  rod  is  kept  as  light  as  it  should  be  in  proportion 
to  the  bob  this  difference  should  come  well  within  the  lim- 
its of  the  adjusting  screw.  In  an  ordinary  plain  seconds 
pendulum,  without  compensation,  with  a  bob  of  eighteen 
or  twenty  pounds  and  a  rod  of  six  ounces,  the  difference  in 
the  two  points  is  of  no  practical  account,  and  adjustments 
for  seconds  are  within  the  screw  of  any  ordinary  pendulum, 
if  the  screw  is  the  right  length  for  safety,  and  the  adjusting 
nut  is  placed  in  the  middle  of  the  length  of  the  screw  threads 


20  THE     MODERN     CLOCK. 

when  the  top  of  the  rod  is  cut  off,  to  place  the  suspen- 
sion spring  by  measurement  from  the  center  of  gravity  as 
has  been  already  described ;  also  a  zinc  and  iron  compensa- 
tion is  within  range  of  the  screw  if  the  compensating  rods 
are  not  made  in  undue  weight  to  the  bob.  The  whole 
v/eight  of  the  compensating  parts  of  a  pendulum  can  be 
safely  made  within  one  and  a  half  pounds  or  lighter,  and 
carry  a  bob  of  twenty-five  pounds  or  over  without  buckling 
the  rods,  and  the  two  points,  the  center  of  gravity  and  the 
center  of  oscillation,  will  be  within  the  range  of  the  screw. 
There  are  still  some  other  forces  to  be  considered  as  af- 
fecting the  performance  of  our  pendulum.  These  are  the 
resistance  to  its  momentum  offered  by  the  air  and  the  resist- 
ance of  the  suspension  spring. 

Barometric  Error. — If  we  adjust  a  pendulum  in  a  clock 
with  an  airtight  case  so  that  the  pendulum  swings  a  certain 
number  of  degrees  of  arc,  as  noted  on  the  degree  plate  in 
the  case  at  the  foot  of  the  pendulum,  and  then  start  to  pump 
out  the  air  from  the  case  while  the  clock  is  running,  we  shall 
find  the  pendulum  swinging  over  longer  arcs  as  the  air  be- 
comes less  until  we  reach  as  perfect  a  vacuuni  as  we  can 
produce.  If  we  note  this  point  and  slowly  admit  air  to  the 
case  again  we  shall  find  that  the  arcs  of  the  pendulum's 
swing  will  -he  slowly  shortened  until  the  pressure  in  the 
case  equals  that  of  the  surrounding  air,  when  they  will  be 
the  same  as  when  our  experiment  was  started.  If  we  now 
pump  air  into  our  clock  case,  the  vibrations  will  become 
still  shorter  as  the  pressure  of  the  air  increases,  proving  con- 
clusively that  the  resistance  of  the  air  has  an  effect  on  the 
swinging  of  the  pendulum. 

We  are  accustomed  to  measure  the  pressure  of  the  air  as 
it  changes  in  varying  weather  by  'means  of  the  barometer 
and  hence  we  call  the  changes  in  the  swing  of  the  pendulum 
due  to  varying  air  pressure  the  ^'barometric  error."  The 
barometric  error  of  pendulums  is  only  considered   in  the 


THE     MODERN     CLOCK.  21 

very  finest  of  clocks  for  astronomical  observatories,  master 
clocks  for  watch  factories,  etc.,  hut  the  resistance  of  the  air 
is  closely  considered  v^hen  we  come  to  shape  our  bob.  This 
is  why  bobs  are  either  double-convex  or  cylindrical  in  shape, 
as  these  two  forms  offer  the  least  resistance  to  the  air  and 
(which  is  more  important)  they  offer  equal  resistance  on 
both  sides  of  the  center  of  the  bob  and  thus  tend  to  keep 
the  pendulum,  swinging  in  a  straight  line  back  and  forth. 

The  Circular  Error. — As  the  pendulum  swings  over  a 
greater  arc  it  will  occupy  more  time  in  doing  it  and  thus 
the  rate  of  the  clock  will  be  affected,  if  the  barometric 
changes  are  very  great.  This  is  called  the  circular  error. 
In  ancient  times,  when  it  was  customary  to  make  pendulums 
vibrate  at  least  fifteen  degrees,  this  error  was  of  importance 


Fig.  4.    A,  arc  of  circle.      B,  cycloid  path  of  pendulum,  exaggerated. 

and  clock  makers  tried  to  make  the  bob  take  a  cycloidal 
path,  as  is  shown  in  Fig.  4,  greatly  exaggerated.  This  was 
accomplished  by  suspending  the  pendulum  by  a  cord  which 
swung  between  cycloidal  cheeks,  but  it  created  so  much  fric- 
tion that  it  was  abandoned  in  favor  of  the  spring  as  used 
to-day.  It  has  since  been  proved  that  the  long  and  short 
arcs  of  the  pendulum's  vibration  are  practically  isochronous 
(with  a  spring  of  proper  length  and  thickness)  up  to  about 
six  degrees  of  arc  (three  degrees  each  side  of  zero  on  the 
degree  plate  at  the  foot  of  the  pendulum)  and  hence  small 
variations  of  power  in  spring-operated  clocks  and  also  the 
barometric  error  are  taken  care  of,  except  for  greatly  in- 
creased variations  of  power,  or  for  too  great  arcs  of  vibra- 
tion. Here  we  see  the  reasons  for  and  the  amount  of  swing 
v»re  can  properly  give  to  our  pendulum. 


22  THE     MODERN     CLOCK. 

Temperature  Error. — The  temperature  error  is  the 
greatest  which  we  shall  have  to  consider.  It  is  this  which 
makes  the  compound  pendulum  necessary  for  accurate  time, 
and  we  shall  consequently  give  it  a  great  amount  of  space, 
as  the  methods  of  overcoming  it  should  be  fully  understood. 

Expansion  of  Metals. — The  materials  commonly  used 
in  m.aking  pendulums  are  wood  (deal,  pine  and  mahogany), 
steel,  cast  iron,  zinc,  brass  and  mercury.  Wood  expands 
.0004  of  its  length  between  32°.  and  212°  F. ;  lead,  .0028; 
steel,  .0011;  mercury,  .0180;  zinc,  .0028;  cast  iron,  .oori ; 
brass,  .0020.  Now  the  length  of  a  seconds  pendulum,  by 
our  tables  (3600  beats  per  hour)  is  0.9939  meter;  if  the  rod 
is  brass  it  will  lengthen  .002  with  such  a  range  of  tempera- 
ture. As  this  is  practically  two-thousandths  of  a  meter,  this 
is  a  gain  of  two  millimeters,  which  would  produce  a  varia- 
tion of  one  minute  and  forty  seconds  every  twenty-fouf 
hours;  consequently  a  brass  rod  would  be  a  very  bad  one. 

If  we  take  two  of  these  materials,  with  as  wide  a  differ- 
ence in  expansion  ratios  as  possible,  and  use  the  least 
variable  for  the  rod  and  the  other  for  the  bob,  supporting  it 
at  the  bottom,  we  can  make  the  expansion  of  the  rod  coun- 
terbalance the  expansion  of  the  bob  and  thus  keep  the  effec- 
tive length  of  our  pendulum  constant,  or  nearly  so.  This  is 
the  theory  of  the  compensating  pendulum. 


CHAPTER  III. 

COMPENSATING   PENDULUMS. 

As  the  pendulum  is  the  means  of  regulating  the  time  con- 
sumed in  unwinding  the  spring  or  weight  cord  by  means 
of  the  escapement,  passing  one  tooth  of  the  escape  wheel 
at  each  end  of  its  swing,  it  will  readily  be  seen  that  length- 
ening or  shortening  the  pendulum  constitutes  the  means  of 
regulating  the  clock;  this  would  make  the  whole  subject  a 
very  simple  affair,  were  it  not  that  the  reverse  proposition 
is  also  true ;  viz. ;  Changing  the  length  of  the  pendulum 
will  change  the  rate  of  the  clock  and  after  a  proper  rate  has 
been  obtained  further  changes  are  extremely  undesirable. 
This  is  what  makes  the  temperature  error  spoken  of  in  the 
preceding  chapter  so  vexatious  where  close  timing  is  de- 
sired and  why  as  a  rule,  a  well  compensated  pendulum  costs 
more  than  the  rest  of  the  clock.  The  sole  reason  for  the 
business  existence  "of  watch  and  clockmakers  lies  in  the 
necessity  of  measuring  time,  and  the  accuracy  with  which 
it  may  be  done  decides  in  large  measure  the  value  of  any 
watchmaker  in  his  community.  Hence  it  is  of  the  utmost 
importance  that  he  shall  provide  himself  with  an  accurate 
means  of  measuring  time,  as  all  his  work  must  be  judged 
finally  by  it,  not  only  while  he  is  working  upon  time-meas- 
uring devices,  but  also  after  they  have  passed  into  the  pos- 
session of  the  general  public. 

A  good  clock  is  one  of  the  very  necessary  foundation 
elements,  contributing  very  largely  to  equip  the  skilled  me- 
chanic and  verify  his  work.  Without  some  reliable  means 
to  get  accurate  mean  time  a  watchmaker  is  always  at  sea — 
without  a  compass — and  has  to  trust  to  his  faith  and  a 

23 


24  THE     MODERN     CLOCK. 

large  amount  of  guessing,  and  this  is  always  an  embarrass- 
ment, no  matter  how  skilled  he  may  be  in  his  craft,  or  adept 
in  guessing.  What  I  want  to  call  particular  attention  to  is 
the  unreliable  and  worthless  character  of  the  average  regu- 
lator of  the  present  day.  A  good  clock  is  not  necessarily  a 
high'  priced  instrument  and  it  is  within  the  reach  of  most 
watchmakers.  A  thoroughly  good  and  reliable  timekeeper 
of  American  make  is  to  be  had  now  in  the  market  for  less 
than  one  hundred  dollars,  and  the  only  serious  charge  that 
can  be  made  against  these  clocks  is  that  they  cost  the  con- 
sumer too  much  money.  Any  of  them  are  thirty-three  and 
a  third  per  cent  higher  than  they  should  be.  About  seventy- 
five  dollars  will  furnish  a  thoroughly  good  clock.  The  aver- 
age clock  to  be  met  with  in  the  watchmakers'  shops  is  the 
Swiss  imitation  •  gridiron  pendulum,  pin  escapement,  and 
these  are  of  the  low  grades  as  a  rule;  the  best  grades  of 
them  rarely  ever  get  into  the  American  market.  Almost 
without  exception,  the  Swiss  regulator,  as  described,  is 
wholly  worthless  as  a  standard,  as  the  pendulums  are  only 
an  imitation  of  the  real  compensated  pendulum.  Tkey  are 
an  imitation  all  through,  the  bob  being  hollow  and  filled 
with  scrap  iron,  and  the  brass  and  steel  rods  composing  the 
compensating  element,  along  with  the  cross  pieces  or  bind- 
ers, are  all  of  the  cheapest  and  poorest  description.  If  one 
of  these  pendulums  was  taken  away  from  the  movement 
and  a  plain  iron  bob  and  wooden  rod  put  to  the  movement, 
in  its  place,  the  possessor  of  any  such  clock  would  be  sur- 
prised to  find  how  m*uch  better  average  rate  the  clock  would 
have  the  year  through,  although  there  would  then  be  no 
compensating  mechanisrh,  or  its  semblance,  in  the  make  up 
of  the  pendulum.  In  brief,  the  average  imitation  compen- 
sation pendulum  of  this  particular  variety  is  far  poorer 
than  the  simplest  plain  pendulum,  such  as  the  old  style, 
grandfather  clocks  were  equipped  with.  A  wood  rod  would 
be  far  superior  to  a  steel  one,  or  any  metal  rod,  as  may  be 
seen  bv  consulting  the  expansion  data  given  in  the  previous 
chapter 


THE     MODERN     CLOCK. 


^5 


Many  other  pendulums  that  are  sold  as  compensating 
are  a  delusion  in  part,  as  they  do  not  thoroughly  compen- 
sate, because  the  elements  composing  them  are  not  in 
equilibrium  or  in  due  proportion  to  one  another  and  to  the 
general  mechanism. 

To  all  workmen  who  have  a  Swiss  regulator,  I  would 
say  that  the  movement,  if  put  into  good  condition,  will  an- 
swer very  well  to  niaintain  the  motion  of  a  good  pendulum, 
and  that  it  will  pay  to  overhaul  these  movements  and  put 
to  them  good  pendulums  that  will  pretty  nearly  compen- 
sate. At  least  a  well  constructed  pendulum  will  give  a 
very  useful  and  reliable  rate  with  such  a  motor,  and  be  a 
great  help  and  satisfaction  to  any  man  repairing  and  rating 
good  watches. 

The  facts  are,  that  one  of  the  good  grade  of  American 
adjusted  watch  movements  will  keep  a  much  steadier  rate 
when  maintained  in  one  position  than  the  average  regulator. 
Without  a  reliable  standard  to  regulate  by,  there  is  very 
little  satisfaction  in  handling  a  good  movement  and  then  not 
be  able  to  ascertain  its  capabilities  as  to  rate.  Very  many 
watch  carriers  are  better  up  in  the  capabilities  of  good 
watches  than  many  of  our  American  repairers  are,  because 
a  large  per  cent  of  such  persons  have  bought  a  watch  of 
high  grade  with  a  published  rate,  and  naturally  when  it  is 
made  to  appear  to  entirely  lack  a  constant  rate  when  com- 
pared with  the  average  regulator,  they  draw  the  conclusion 
that  the  clock  is  at  fault,  or  that  the  cleaning  and  repairing 
are.  Many  a  fair  workman  has  lost  his  watch  trade,  largely 
on  account  of  a  lack  of  any  kind  of  reliable  standard  of 
time  in  his  establishment.  There, are  very  few  things  that 
a  repairer  can  do  in  the  way  of  advertising  and  holding  his 
customers  more  than  to  keep  a  good  clock,  and  furnish 
good  watch  owners  a  means  of  comparison  and  thus  to  con- 
firm their  good  opinions  of  their  watches. 

We  have  along  our  railroads  throughout  the  country  a 
standard  time  system  of  synchronized  clocks,  which  are  an 


26  THE     MODERN     CLOCK. 

improvement  over  no  standard  of  comparison;  but  they 
cannot  be  depended  upon  as  a  reliable  standard,  because 
they  are  subject  to  all  the  uncertainties  that  affect  the  tele- 
graph lines^ — bad  service,  lack  of  skill,  storms,  etc.  The 
clocks  furnished  by  these  systems  are  not  reliable  in  them- 
selves and  they  are  therefore  corrected  once  in  twenty-four 
hours  by  telegraph,  being  automatically  set  to  mean  time  by 
the  mechanism  for  that  purpose,  which  is  operated  by  a 
standard  or  master  clock  at  some  designated  point  in  the 
system. 

Now  all  this  is  good  in  a  general  way ;  but  as  a  means  to 
regulate  a  fine  watch  and  use  as  a  standard  from  day  to 
day,  it  is  not  adequate.  A  standard  clock,  to  be  thoroughly 
serviceable,  must  always,  all  through  the  twenty-four  hours, 
have  its  seconds  hand  at  the  correct  point  at  each  minute 
and  hour,  or  it  is  unreliable  as  a  standard.  The  reason  is 
that  owing  to  train  defects  watches  may  vary  back  and 
forth  and  these  errors  cannot  be  detected  with  a  standard 
that  is  right  but  once  a  day.  No  man  can  compare  to  a 
certainty  unless  his  standard  is  without  variation,  substan- 
tially ;  and  I  do  not  know  of  any  way  that  this  can  be  ob- 
tained so  well  and  satisfactorily  as  through  the  means  of 
a  thoroughly  good  pendulum. 

Compensating  seconds  pendulums  are,  it  might  be  said, 
the  standard  time  measure.  Mechanically  such  a  pendulum 
is  not  in  any  way  difficult  of  execution,  yet  by  far  the 
greater  portion  of  pendulums  beating  seconds  are  not  at  all 
accurate  time  measures,  as  independently  of  their  slight 
variations  in  length,  any  defects  in  the  construction  or  fit- 
ting of  their  parts  are  bound  to  have  a  direct  effect  upon 
the  performance  of  the  clock.  The  average  watchmaker 
as  a  mechanic  has  the  ability  to  do  the  work  properly,  but 
he  does  not  fully  understand  or  realize  what  is  necessary, 
nor  appreciate  the  fact  that  little  things  not  attended  to 
will  render  useless  all  his  efforts. 

The  first  consideration  in  a  compensated  pendulum  is  to 


THE     MODERN     CLOCK.  27 

maintain  the  center  of  oscillation  at  a  fixed  distance  from 
the  point  of  suspension  and  it  does  not  matter  how  this  is 
accomplished. 

So,  also,  the  details  of  construction  are  of  little  conse- 
quence, so  long  as  the  main  points  are  well  looked  after — 
the  perfect  solidity  of  all  parts,  with  very  few  of  them,  and 
the  free  movement  of  all  working  surfaces  without  play,  so 
that  the  compensating  action  may  be  constantly  maintained 
at  all  times.  Where  this  is  not  the  case  the  sticking,  rat- 
tling, binding  or  cramping  of  certain  parts  will  give  differ- 
ent rates  at  different  times  under  the  same  variations  of 
temperature,  according  as  the  parts  work  smoothly  and 
evenly  or  move  only  by  jerks. 

The  necessary  and  useful  parts  of  a  pendulum  are  all  that 
are  really  admissible  in  thoroughly  good  construction.  Any 
and  all  pieces  attached  by  way  of  ornament  merely  are  apt 
to  act  to  the  prejudice  of  the  necessary  parts  and  should 
be  avoided.  In  this  chapter  we  shall  give  measurements 
and  details  of  construction  for  a  number  of  compensated 
pendulums  of  various  kinds,  as  that  will  be  the  best  means 
of  arriving  at  a  thorough  understanding  of  the  subject, 
even  if  the  reader  does  not  desire  to  construct  such  a  pen- 
dulum for  his  own  use. 

Principles  of  Construction. — Compensation  pendu- 
lums are  constructed  upon  two  distinct  principles.  First, 
those  in  which  the  bob  is  supported  by  the  bottom,  resting 
on  the  adjusting  screw  with  its  entire  height  free  to  expand 
upward  as  the  rod  expands  downward  from  its  fixed  point 
of  suspension.  In  this  class  of  pendulums  the  error  of  the 
bob  is  used  to  counteract  that  of  the  rod  and  if  the  bob  is 
made  of  sufficiently  expansible  metal  it  only  remains  to 
make  the  bob  of  sufficient  height  in  proportion  to  its  ex- 
pansibility for  one  error  to  offset  the  other.  In  the  second 
class  the  attempt  is  made  to  leave  out  of  consideration  any 
errors  caused  by  expansion  of  the  bob,  by  suspending  it 


28  THE     MODERN     GLQCK. 

from  the  center,  so  that  its  expansion  downward  will  ex- 
actly balance  its  expansion  upward, and  hence  they  will  bal- 
ance each  other  and  may  be  neglected.  Having,  eliminated 
the  bob  from  consideration  by  this  m^ans  we  must  neces- 
sarily confine  our  attempt  at  compensation  to  the  rod  in  the 
second  method. 

The  wood  rod  and  lead  bob  and  the  mercurial  pendulums 
are  examples  of  the  first-class  and  the  wood  rod  with  brass 
sleeve  having  a  nut  at  the  bottom  and  reaching  to  the  center 
of  the  iron  bob  and  the  common  gridiron,  or  compound 
tubular  rod,  or  compound  bar  of  steel  and  brass,  or  -steel 
and  zinc,  are  examples  of  the  second  class. 

Wood  Rod  and  Zinc  Bob. — We  will  suppose  that  we 
have  one  of  the  Swiss  imitation  gridiron  pendulums  which 
we  want  to  discard,  while  retaining  the  case  and  movement. 
As  these  cases  are  wide  and  generally  fitted  with  twelve- 
inch  dials,  we  shall  have  about  twenty  inches  inside  our  case 
and  we  may  therefore  use  a  large  bob,  lens-shaped,,  made  of 
cast  zinc,  polished  and  lacquered  to  look  like  brass. 

The  bobs  in  such  imitation  gridiron  pendulums  are  gener- 
ally about  thirteen  inches  in  diameter  and  swing  about  five 
inches  (two  and  a  half  inches  each  side).  The.  pendulums 
are  generally  light,  convex  in  front  and  flattened  at  the 
rear,  and  the  entire  pendulum  measures  about  56  inches 
from  the  point  of  suspension  to  the  lower  end  of  the  adjust- 
ing screw.  We  will  also  suppose  that  we  desire  to  change 
the  appearance  of  the  clock  as  little  as  possible,  while  im- 
proving its  rate.  This  will  mean  that  we  desire  to  retain  a 
lens-shaped  bob  of  about  the  same  size  as  the  one  we  are 
going  to  remove. 

We  shall  first  need  to  know  the  total  length  of  our  pen- 
dulum, so  that  we  can  calculate  the  expansion  of  the  rod. 
A  seconds  pendulum  measures  39.2  inches  from  the  point 
in  the  suspension  spring  at  the  lower  edge  of  the  chops  to 
the  center  of  oscillation.    With  a  lens-shaped  bob  the  center 


THE     MODERN     CLOCK.  *     '29 

of  gravity  will  be  practically  at  the  center  of  the  bob,  if  we 
use  a  light  \vooden  rod  arid  a  steel  adjusting  screw  and 
brass  nut,  as  these  metal  parts,  although  short,  will  be 
heavy  enough  to  nearly  balance  the  suspension  spring  and 
that  portion  of  the  rod  which  is  above  the  center.  We  shall 
also  gain  a  little  in  balance  if  we  leave  the  steel  screw. long 
enough  to  act  as  an  index  over  the  degree  .plate,  in  the  case, 
at  the  bottom  of  the  pendulum,  by  stripping  the  thread  and 
turning  the  end  to  a  taper  an  inch  or  so  in  length. 

We  shall  only  be  able  to  use  one-half  of  the  expansion 
upwards  of  our  bob,  because  the  centers  of  gravity  and  os- 
cillation will  be  practically  together  at  the  center  of  the  bob. 
We  shall  find  the  center  of  gravity  easily  by  balancing  the 
pendulum  on  a  knife-edge  and  thus  we  will  be  able  to  make 
an  exceedingly  close  guess  at  the  center  of  oscillation. 

Now,  looking  over  our  data,  we  find  that  we  have  a  sus- 
pension spring  of  steel,  then  some  wood  and  steel  again  at 
the  other  end.  We  shall  need  about  one  inch  of  suspension 
spring.  The  spring  will,  of  course,  be  longer  than  one 
inch,  but  we  shall  hold  it  in  iron  chops  and  the  expansion 
of  the  chops  will  equal  that  of  the  spring  between  them,  so 
that  only  the  free  part  of  the  spring  need  be  considered. 
Now  from  the  adjusting  screw,  where  it  leaves  the  last 
pin  through  the  wood,  to  the  middle  position  of  the  rating 
nut  will  be  about  one  inch,  so  we  shall  have  two  inches  of 
steel  to  consider  in  our  figures  of  expansion. 

Now  to  get  the  length  of  the  rod.  We  want  to  keep  our 
bob  about  the  size  of  the  other,  so  we  will  try  14  inches 
diameter,  as  half  of  this  is  an  even  number  and  makes  easy 
figuring  in  our  trials.  39.2  inches,  plus  7  (half  the  diameter 
of  the  bob)  gives  us  46.2  inches;  now  we  have  an  inch  of 
adjustment  in  our  screw,  so  we  can  discard  the  .2;  this 
leaves  us  46  inches  of  wood  and  steel  for  which  we  must 
get  the  expansion. 


JO   ♦  THE    MODERN    CLOCK. 

Wood  expands  .0004  of  its  length  between  32°  and  212°  F. 
Steel  expands  .0011  of  its  length  between  32°  and  212°  F. 
Lead  expands  .0028  of  its  length  between  32°  and  212°  F. 
Brass  expands  .0020  of  its  length  between  32**  and  212"  F. 
Zinc  expands  .0028  of  its  length  between  32**  and  212°  F. 
Tin  expands  .0021  of  its  length  between  32**  and  212°  F. 
Antimony  expands  .0011  of  its  length  between  32°  and  212°  F. 
Total  length  of  pendulum  to  adjusting  nut  46  inches. 
Total  length  of  steel  to  adjusting  nut  2  inches. 
Total  length  of  wood  to  adjusting  nut  44  inches. 
,0011  X    2  =  .0022  inch,  expansion  of  our  steel. 
.0004  X  44:=  .0176  inch,  expansion  of  our  wood. 


.0198  total  expansion  of  rod. 

We  have  7  inches  as  half  the  diameter  of  our  bob 
.0198  -^  7  =  .0028  2-y,  which  we  find  from  our  tables  is 
very  close  to  the  expansion  of  zinc,  so  we  will  make  the  bob 
of  that  metal."  Now  let  us  check  back ;  the  upward  expan- 
sion of  7  inches  of  zinc  equals  .0028  X  .7  ^  .0196  inch,  as 
against  .0198  inch  downward  expansion  of  the  rod.  This 
gives  us  a  total  difference  of  .0002  inch  between  32°  and 
212°  or  a  range  of  180°  F.  This  is  a  difference  of  .0001 
inch  for  90°  of  temperature  and  is  closer  than  most  pendu- 
lums ever  get. 

The  above  figures  are  for  dry,  clear  white  pine,  well 
baked  and  shellacked,  with  steel  of  average  expansion,  and 
zinc  of  new  metal,  melted  and  cast  without  the  admixtures 
of  other  metals  or  the  formation  of  oxide.  The  presence 
of  tin,  lead,  antimony  and  other  admixtures  in  the  zinc 
would  of  course  change  the  results  secured;  so  also  will 
there  be  a  slight  difference  in  the  expansion  of  the  rod  if 
other  woods  are  used.  Still  the  jeweler  can  from  the  above 
get  a  very  close  approximation. 

Such  a  bob,  14  inches  diameter  and  1.5  inches  thick,  alike 
on  both  sides,  with  an  oval  hole  ix.5  inches  through  its  cen- 
ter, see  Fig.  5,  would  weigh  about  30  to  32  pounds,  and 


THE     MODERN    CLOCK. 


31 


f 


o ,        o 

Tor 

I 


Fig.  5.    Zinc  bob  and  wood  rod  to  replace  imitation  gridiron  pendulum. 


32 


THE     MODERN     CLOCK. 


would  have  to  be  hung  from  a  cast  iron  bracket,  Fig.  6, 
bolted  through  the  clock  case  to  the  wall  behind  it,  so  as  to 
get  a  steady  rate.  It  would  be  nearly  constant,  as  the  metal 
is  spread  out  so  as  to  be  quickly  affected  by  temperature; 
and  the  shape  would  hold  it  well  in  its  plane  of  oscillation, 
if  both  sides  were  of  exactly  the  same  curvature,  while  the 


n 


Fig.  G.    Cast  iron  bracket  for  lieavy  pendulums  and  movements. 

weight  would  overcome  minor  disturbances  due  to  vibration 
of  the  building.  It  would  require  a  little  heavier  suspension 
spring,  in  order  to  be  isochronous  in  the  long  and  short 
arcs  and  this  thickening  of  the  spring  would  need  the  addi- 
tion of  from  one  and  a  half  to  two  pounds  rnore  of  driving 
weight. 

If  so  heavy  a  pendulum  is  deemed  undesirable,  the  bob 
would  have  to  be  made  of  cylindrical  form,  retaining  the 
height,  as  necessary  to  compensation,  and  varying  the  diam- 
eter of  the  cylinder  to  suit  the  weight  desired. 


Wood  Rod  and  Lead  Bob. — The  wood  should  be  clear, 
straight-grained  and  thoroughly  dried,  then  given  several 
coats  of  shellac  varnish,  well  baked  on.     It  may  be  either 


THE     MODERN     CLOCK. 


33 


Fig.  7.    "Wood  rod  and 
lead  bob. 


Fig.  8.    Bob  of  metal  casing 
filled  with  shot. 


34  THE     MODERN     CLOCK. 

flat,  oval  or  round  in  section,  but  is  generally  made  round 
because  the  brass  cap  at  the  upper  end,  the  lining  for  the 
crutch,  and  the  ferrule  for  the  adjusting  screw  at  the  lower 
end  may  then  be  readily  made  from  tubing.  For  pendu- 
lums smaller  than  one  second,  the  wood  is  generally  hard, 
as  It  gives  a  firmer  attachment  of  the  metal  parts. 

Inches. 

Length,  top  of  suspension  spring  to  bottom  of  bob 44.S 

Length  to  bottom  of  nut 45.25 

Diameter  of  bob 2.0 

Length  of  bob 10.5 

V/eight  of  bob,  3  lbs. 

Acting  length   of   suspension   spring i.o 

Width   of   spring    45 

Thickness .008 

Diameterr  of  rod    5 

The  top  of  the  rod  should  have  a  brass  collar  fixed  on  it 
by  riveting  through  the  rod  and  it  should  extend  down  the 
rod  about  three  inches,  so  as  to  make  a  firm  support  for  the 
slit  to  receive  the  lower  clip  of  the  suspension  spring.  The 
lower  end  should  have  a  slit  or  a  round  hole  drilled  longi- 
tudinally three  inches  up  the  rod  to  receive  the  upper  end  of 
the  adjusting  screw  and  this  should  also  fit  snugly  and  be 
well  pinned  or  riveted  in  place.  See  Fig.  7.  A  piece  of 
thin  brass  tube  about  one  inch  in  length  is  fitted  over  the 
rod  where  the  crutch  works. 

In  casting  zinc  and  lead  bobs,  especially  those  of  lens- 
shapes,  the  jeweler  should  not  attempt  to  do  the  work  him- 
self, but  should  go  to  a  pattern  maker,  explain  carefully 
just  what  is  wanted  and  have  a  pattern  made,  as  such  pat- 
terns must  be  larger  than  the  casting  in  order  to  take  care 
of  the  shrinkage  due  to  cooling  the  molten  metal.  It  will 
also  be  better  to  use  an  iron  core,  well  coated  with  graphite 
when  casting,  as  the  core  can  be  made  smooth  throughout 
and  the  exact  shape  of  the  pendulum  rod,  and  there  will 
then  be  no  work  to  be  done  on  the  hole  when  the  casting 
is  made.     The  natural  shrinkage  of  the  metal  on  cooling 


THE     MODERN     CLOCK.  3^ 

will  free  the  core,  which  can  be  easily  driven  out  when 
the  metal  is  cc5ld  and  it  will  then  leave  a  smooth,  well 
shaped  hole  to  which  the  rod  can  be  fitted  to  work  easily, 
but  without  shake.  Lens-shaped  bobs,  particularly,  should 
be  cast  flat,  with  register  pins  on  the  flask,  so  as  to  get  both 
sides  central  with  the  hole,  and  be  cast  with  a  deep  riser 
large  enough  to  put  considerable  pressure  of  melted  metal 
on  the  casting  until  it  is  chilled,  so  as  to  get  a  sound  cast- 
ing ;  it  should  be  allowed  to  remain  in  the  sand  until  thor- 
oughly cold,  for  the  same  reason,  as  if  cooled  quickly  the 
bob  will  have  internal  stresses  which  are  liable  to  adjust 
themselves  sometime  after  the  pendulum  is  in  the  clock 
and  thus  upset  the  rate  until  such  interior  disturbances  have 
ceased.  Cylinders  may  be  cast  in  a  length  of  steel  tubing, 
using  a  round  steel  core  and  driven  out  when  cold. 

If  using  oval  or  flat  rods  of  wood,  the  adjusting  screw 
should  be  flattened  for  about  three  inches  at  its  upper  end, 
wide  enough  to  conform  to  the  width  of  the  rod ;  then  saw 
a  slot  in  the  center  of  the  rod,  wide  and  deep  enough  to  just 
fit  the  flattened  part  of  the  screw ;  heat  the  screw  and  apply 
shellac  or  lathe  wax  and  press  it  firmly  into  the  slot  with 
the  center  of  the  screw  in  line  with  the  center  of  the  rod; 
after  the  wax  is  cold  select  a  drill  of  the  same  size  as  the 
rivet  wire;  drill  and  rivet  snugly  through  the  rod,  smooth 
everything  carefully  and  the  job  is  complete. 

If  by  accident  you  have  got  the  rod  too  small  for  the  hole, 
so  that  there  is  any  play,  give  the-  rod  another  coat  of 
shellac  varnish  and  after  drying  thoroughly,  sand  paper  it 
down  until  it  will  fit  properly. 

Round  rods  may  be  treated  in  the  same  manner,  but  it  is 
usual  to  drill  a  round  hole  in  such  a  rod  to  just  fit  the 
wire,  then  insert  and  rivet  as  before  after  the  wax  is  cold, 
finishing  with  a  ferrule  or  cap  of  brass  at  the  end  of  the 
rod. 

The  slot  for  the  suspension  spring  is  fitted  to  the  upper 
end  of  the  rod  in  the  same  manner. 


36  THE     MODERN     CLOCK. 

Pendulum  with  Shot. — Still  another  method  of  mak- 
ing a  compensating  pendulum,  which  gives  a  lighter  pendu- 
lum, is  to  make  a  case  of  light  brass  or  steel  tubing  of  about 
three  inches  diameter.  Fig.  8,  with  a  bottom  and  top  of 
equal  weight,  so  as  to  keep  the  center  of  oscillation  about 
the  center  of  gravity,  for  convenience  in  working.  The  bot- 
tom may  be  turned  to  a  close  fit,  and  soldered,  pinned,  or 
riveted  into  the  tube.  It  is  pierced  at  its  center  and  another 
tube  of  the  same  material  as  the  outer  tube,  with  an  internal 
diameter  which  closely  fits  the  pendulum  rod  is  soldered  or 
riveted  into  the  center  of  the  bottom,  both  bottom  and  top 
being  pierced  for  its  admission  and  the  other  parts  fitted  as 
previously  described. 

The  length  of  the  case  or  canister  should  be  about  11.5 
inches  so  as  to  give  room  for  a  column  of  shot  of  10.5 
inches  (the  normal  compensating  height  for  lead)  and  still 
leave  room  for  correction.  Make  a  tubular  case  for  the 
driving  weight  also  and  then  we  have  a  flexible  system. 
If  it  is  necessary  to  add  or  subtract  weight  to  obtain  the 
proper  arcs  of  oscillation  of  the  pendulum,  it  can  be  readily 
done  by  adding  to  or  taking  from  the  shot  in  the  weight 
case. 

Fill  the  pendulum  to  10.5  inches  with  ordinary  sports- 
men's shot  and  try  it  for  rate.  If  it  gains  in  heat  and  loses 
in  cold  it  is  over-compensated  and  shot  must  be  taken  from 
it.  If  it  loses  in  heat  and  gains  in  cold  it  is  under-com- 
pensated and  shot  should  be  added. 

The  methods  of  calculation  were  given  in  full  in  describ- 
ing the  zinc  pendulum  and  hence  need  not  be  repeated  here,, 
but  attention  should  be  called  to '  the '  fact  that  there  are 
three  materials  here,  wood,  steel  or  brass  and  lead  and  each 
should  be  figured  separately  so  that  the  last  two  may  just 
counterbalance  the  first.  If  the  case  is  made  light  through- 
out the  effect  upon  the  center  of  oscillation  will  be  inappre- 
ciable as  compared  with  that  of  the  lead,  but  if  made 
heavier  than  need  be,  it  will  exert  a  marked  influence,  par« 


THE     MODERN     CLOCK. 


37 


ticularly  if  its  highest  portion  (the  cover)  be  heavy,  as  we 
then  have  the  effect  of  a  shifting  weight  high  up  on  the 
pendulum  rod.  If  made  of  thin  steel  throughout  and  nickel 
plated,  we  shall  have  a  light  and  handsome  case  for  our 
bob.  If  this  is  not  practicable,  or  if  the  color  of  brass  be 
preferred,  it  may  be  made  of  that  material. 

The  following  table  of  weights  will  be  of  use  in  making 
calculations  for  a  pendulum  or  for  clock  weights. 

"Weight  of  Lead,  Zinc  and  Cast  Iron  Cylinders  One  Half  Inch  Long. 


Diameter 

Weight  in  Pounds 

Diameter 
in  Inches 

Weight  in  Pounds 

in  Inches. 

Lead 

Zinc 

Iron 

Lead 

Zinc 

Iron 

.25 

.020 

.012 

.012 

3  25 

3  400 

2.098 

2.156 

.5 

.080 

.049 

.050 

3  5 

3.944 

2.434 

2.491 

.75 

.180 

.111 

.114 

3  75 

4  51 

2.783 

2  865 

1 

.321 

.198 

.204 

4 

5149 

3.177 

3.265 

1.25 

.503 

.310 

.319 

4  25 

5  813 

3.587 

3  686 

1.5 

.724 

.447 

.459 

4.5 

6  619 

3  922 

4.134 

1.75 

.984 

.607 

.624 

4.75 

7  265 

4  483 

4.607 

2. 

1.287 

.794 

.816 

5 

8  048 

4966 

5.103 

2  25 

1630 

1.005 

1033 

5.25 

8  872 

5.474 

5.626 

2.5 

2.009 

2  239 

1274 

5  5 

9  737 

6.008 

5.175 

2.75 

2.434 

1502 

1544 

5.75 

10.643 

6.567 

6.749 

3. 

2.897 

1788 

1837 

6 

11.590 

7.152 

7.350 

Example:— Required,  the  weight  of  a  lead  pendulum  bob,  3 
inches  diameter,  9  inches  long,  which  has  a  hole  through  it  .75  inch 
in  diameter.  The  weight  of  a  lead  cylinder  3  inches  diameter  i.a  the 
table  is  2  897,  which  multiplied  by  9  (the  length  given)=26.07  lbs. 
Then  the  weight  in  the  table  of  a  cylinder  .75  inch  diameter  is  .18 
and  .18X9  =  1.62  lbs.  And  26.07  -  1.62=24.45.  the  weight  required  in 
lbs. 


Auxiliary  Weights. — If  for  any  reason  our  pendulum 
does  not  turn  out  with  a  rating  as  calculated  and  we  find 
after  getting  it  to  time  that  it  is  over  compensated,  it  is  a 
comparatively  simple  matter  to  turn  off  a  portion  from  the 
bottom  of  a  solid  bob.  By  doing  this  in  very  small  por- 
tions at  a  time  and  then  testing  carefully  for  heat  and  cold 
every  time  any  amount  has  been  removed,  we  shall  in  the 


38  THE     MODERN     CLOCK. 

course  of  a  few  weeks  arrive  at  a  close  approximation  to 
compensation,  at  least  as  close  as  the  ordinary  standards 
available  to  the  jeweler  will  permit.  This  is  a  matter  of 
weeks,  because  if  the  pendulum  is  being  rated  by  the  stan- 
dard time  which  is  telegraphed  over  the  country  daily  at 
noon,  the  jeweler,  as  soon  as  he  gets  his  pendulum  nearly 
right,  will  begin  to  discover  variations  in  the  noon  signal  of 
from  .2  to  5  seconds  on  successive  days.  Then  it  becorhes 
a  matter  of  averages  and  reasoning,  thus:  If  the  pendu- 
lum beats  to ,  time  on  the  first,  second,  third,  fifth  and 
seventh  days,  it  follows  that  the  signal  w^as  incorrect — slow 
or  fast— on  the  fourth  and  sixth  days. 

If  the  pendulum  shows  a  gain  of  one  second  a  week  on 
the  majority  of  the  days,  the  observation  must  be  continued 
without  changing  the  pendulum  for  another  week.  If  the 
pendulum  shows  two  seconds  gain  at  the  end  of  this 
time,  we  have  tw^o  things  to  consider.  Is  the  length  right, 
or  is  the  pendulum  not  fully  compensated?  We  cannot  an- 
swer the  second  query  without  a  record  of  the  temperature 
variations  during  the  period  of  observations. 

To  get  the  temperature  record  we  shall  require  a  set  of 
maximum  and  minimum  thermometers  in  our  clock  case. 
They  consist  of  mercurial  thermometer  tubes  on  the  ordi- 
nary Fahrenheit  scales,  but  with  a  marker  of  colored  wood 
or  metal  resting  on  the  upper  end  of  the  column  of  mercury 
in  the  tube.  The  tube  is  not  hung  vertically,  but  is  placed 
in  an  inclined  position  so  that  the  mark  will  stay  where  it 
is  pushed  by  the  column  of  mercury.  Thus  if  the  tem- 
perature rises  during  the  day  to  84  degrees  the  mark  in  the 
maximum  thermometer  will  be  found  resting  in  the  tube 
at  84°  whether  the  mercury  is  there  when  the  reading  is 
taken  or  not.  Similarly,  if  the  temperature  has  dropped 
during  the  night  to  40°,  the  mark  in  the  minimum  ther- 
mometer will  be  found  at  40°,  although  the  temperature 
may  be  70°  w^hen  the  reading  is  taken.  After  reading,  the 
thermometers  are  shaken  to  bring  the  marks  back  to  the  top 


THE     MODERN     CLOCK. 


39 


of  the  column  of  mercury  and  the  thermometers  are  then 
restored  to  their  positions,  ready  for  another  reading  on  the 
following  day. 

These  records  should  be  set  down  on  a  sheet  every  day 
at  noon  in  columns  giving  date,  rate,  plus  or  minus,  maxi- 
mum, minimum,  average  temperature  and  remarks  as  to 
regulation,  etc.,  and  with  these  data  to  guide  us  we  shall  be 
in  a  position  to  determine  whether  to  move  the  rating  nut  or 
not.  If  the  temperature  has  been  fairly  constant  we  can 
get  a  closer  rate  by  moving  the  nut  and  continuing  the  ob- 
servations. If  the  temperature  has  been  increasing  steadily 
and  our  pendulum  has  been  gaining  steadily  it  is  probably 
over-compensated  and  the  bob  should  be  shortened  a  trifle 
and  the  observations  renewed. 

It  is  best  to  ''make  haste  slowly"  in  such  a  matter.  First 
bring  the  pendulum  to  time  in  a  constant  temperature ;  that 
will  take  care  of  its  proper  length.  Then  allow  the  tem- 
perature to  vary  naturally  and  note  the  results. 

If  the  pendulum  is  under-compensated,  so  that  the  bob  is 
too  short  to  take  care  of  the  expansion  of  the  rod,  auxiliary 
weights  of  zinc  in  the  shape  of  washers  (or  short  cylinders) 
are  placed  between  the  bottom  of  the  bob  and  the  rating 
nut.  This  of  course  makes  necessary  a  new  adjustment  and 
another  course  of  observations  all  around,  but  it  will  readily 
be  seen  that  it  places  a  length  of  expansible  metal  between 
the  nut  and  the  center  of  oscillation  and  thus  makes  up  for 
the  deficiency  of  expansion  of  the  bob.  Zinc  is  generally 
chosen  on  account  of  its  high  rate  of  expansion,  but  brass, 
aluminum  and  other  metals  are  also  used.  It  is  best  to  use 
one  thick  washer,  rather  than  a  number  of  thinner  ones,  as 
it  is  important  to  keep  the  construction  as  solid  at  this  point 
as  possible. 

Top  Weights. — After  bringing  the  pendulum  as  close 
as  possible  by  the  compensation  and  the  rating  nuts,  astron- 
omers and  others  requiring  exact  time  get  a  trifle  closer  rat- 


40  THE     MODERN     CLOCK. 

ing  by  the  use  of  top  weights.  These  are  generally  U- 
shaped  pieces  of  thin  metal  which  are  slipped  on  the  rod 
above  the  bob  without  stopping  the  pendulum.  They  raise 
the  center  of  oscillation  by  adding  to  the  height  of  the  bob 
when  they  are  put  on,  or  lower  it  when  they  are  removed, 
but  they  are  never  resorted  to  until  long  after  the  pendulum 
is  closer  to  time  than  the  jeweler  can  get  with  his  limited 
standards  of  comparison.  They  are  mentioned  here  simply 
that  their  use  may  be  understood  when  they  may  be  encoun- 
tered in  cleaning  siderial  clocks. 

Mercurial  pendulums  also  belong  to  the  class  of  com- 
pensation by  expansion  of  the  bobs,  but  they  are  so  numer- 
ous and  so  different  that  they  will  be  considered  separately, 
later  on. 

Compensated  Pendulum  Rods. — We  will  now  consider 
the  second  class,  that  in  which  an  attempt  is  made  to  obtain 
a  pendulum  rod  of  unvarying  length. 

The  oldest  form  of  compensated  rod  is  undoubtedly  the 
gridiron  of  either  nine,  five  or  three  rods.  As  originally 
made  it  was  an  accurate  but  expensive  proposition,  as  the 
coefficients  of  expansion  of  the  brass  or  zinc  and  iron  or 
steel  had  all  to  be  determined  individually  for  each  pendu- 
lum. Each  rod  had  to  be  sized  accurately,  or  if  this  was 
not  done,  then  each  rod  had  to  be  fitted  carefully  to  each 
hole  in  the  cross  bars  so  as  to  move  freely,  without  shake. 
The  rods  were  spread  out  for  two  purposes,  to  impress 
the  public  and  to  secure  uniform  and  speedy  action  in 
changes  of  temperature.  The  weight,  which  increased 
rapidly  with  the  increase  of  diameter  of  the  rod,  made  a 
long  and  large  seconds  pendulum,  some  of  them  measuring 
as  much  as  sixty-two  inches  in  length,  and  needing  a  large 
bob  to  look  in  proportion.  Various  attempts  w^ere  made 
to  ornament  the  great  expanse  of  the  gridiron,  harps, 
wreaths  and  other  forms  in  pierced  metal  being  screwed 
to  the  bars.    The  next  advance  was  in  substituting  tubes  for 


THE     MODERN     CLOCK.  4I 

rods  in  the  gridiron,  securing  an  apparently  large  rod  that 
was  at  the  same  time  stiff  and  light.  Then  came  the  era  of 
imitation,  in  which  the  rods  were  made  of  all  brass,  the 
imitation  steel  portion  being  nickel  plated.  With  the  devel- 
opment of  plating  they  were  still  further  cheapened  by 
being  made  of  steel,  with  the  supposedly  brass  rods  plated 
with  brass  and  the  steel  ones  with  nickel.  Thousands  of 
such  pendulums  are  in  use  to-day ;  they  have  the  rods  riv- 
eted to  the  cross-pieces  and  are  simply  steel  rods,  subject  to 
change  of  length  with  every  change  in  temperature.  It 
does  no  harm  to  ornament  such  pendulums,  as  the  rods 
themselves  are  merely  ornaments,  usually  all  of  one  metal, 
plated  to  change  the  color. 

As  three  rods  were  all  that  were  necessary,  the  clock- 
maker  who  desired  a  pendulum  that  was  compensated  soon 
found  his  most  easily  made  rod  consisted  of  a  zinc  bar, 
wide,  thin  and  flat,  placed  between  two  steel  parts,  like  the 
meat  and  bread  of  a  sandwich.  This  gives  a  flat  and  appar- 
ently solid  rod  of  metal  which  if  polished  gives  a  pleasing 
appearance,  and  combines  accurate  performance  with  cheap- 
ness of  construction,  so  that  any  watchmaker  may  make  it 
himself,  without  expensive  tools. 

Flat  Compensated  Rod. — One  of  the  most  easily  made 
zinc  and  iron  compensating  pendulums,  shown  in  detail  in 
Fig.  9,  is  as  follows :  A  lead  or  iron  bob,  lens  shaped,  that 
is,  convex  equally  on  each  side,  9  inches  diameter  and  an 
inch  and  one-quarter  thick  at  the  center.  A  hole  to  be 
made  straight  through  its  diameter  ^  inch.  One-half 
through  the  diameter  this  hole  is  to  be  enlarged  to  ^4,  inch 
diameter.  This  will  make  the  hole  for  half  of  its  length 
]/2  inch  and  the  remaining  half  ^  inch  diameter.  The 
%  hole  must  have  a  thin  tube,  just  fitting  it,  and  5  inches 
long.  At  one  end  of  this  tube  is  soldered  in  a  nut,  with  a 
hole  tapped  with  a  tap  of  thirty-six  threads  to  the  inch,  and 
}i    inch    diameter,    and   at   the   other   end   of   the   tube    is 


42 


THE     MODERN     CLOCK. 


A,  the  lens-shaped  bob;  T  P,  the 
total  length  of  the  compensating 
part. 

R,  the  upper  round  part  of  rod. 

The  side  showing  the  heads  of 
the  screws  is  the  face  side  and  is 
finished.  The  screws  1,2,3,4  hold 
the  three  pieces  from  separating, 
but  do  not  confine  the  front  and 
middle  sections  in  their  lengthwise 
expansion  along  the  rod,  but  are 
screwed  into  the  back  iron  section, 
while  the  holes  in  the  other  two 
sections  are  slotted  smaller  than 
the  screw  heads. 

The  holes  at  the  lower  extreme 
of  combination  5,  6,  7,  8,  9  are  for 
adjustments  in  effecting  a  com- 
pensation. 

The  pin  at  10  is  the  steel  adjusting 
pin,  and  is  only  tight  in  the  front 
bar  and  zinc  bars,  being  loose  in 
the  back  bar. 

0  and  P  show  the  angles  in  the 
back  rod,  T  shows  the  angle  in  the 
rod  at  the  top,  m  shows  the  pin  as 
placed  in  the  iron  and  zinc  sections 
wherfe  they  have  been  soldered  as 
described. 

h  shows  the  regulating  nut  car- 
ried by  the  tube,  as  described,  and 
terminating  in  the  nut  D. 

1  and  i  show  the  screw  of  36  threads. 
The  nut  D  is  to  be  divided  on  its 

edge  into  30  divisions. 

n  is  the  angle  of  the  back  bar  to 
which  zinc  is   soldered. 


Fig.  9.    Pendulum  with  compensated  rod  of  steel  and  zinc. 


THE    MODERN    CLOCK.  43 

soldered  a  collar  or  disc  one  inch  diameter,  which  is  to  be 
divided  into  thirty  divisions,  for  regulating  purposes,  as  will 
be  described  later  on.  The  whole  forms  a  nut  into  which 
the  rod  screws,  and  the  tube  allows  the  nut  to  be  pushed 
up  to  the  center  of  the  diameter  of  the  bob,  through  the 
large  hole,  and  the  nut  can  be  operated  then  by  means  of 
the  disc  at  its  lower  end.  The  rod,  of  flat  iron,  is  in  two  sec- 
tions, as  follows :  That  section  which  enters  the  bob  and 
terminates  in  the  regulating  screw  is  flat  for  twenty-six 
inches,  and  then  rounded  to  Yz  inch  for  six  inches,  and  a 
screw  cut  on  its  end  for  two  inches,  to  fit  the  thread  in  the 
nut.  The  upper  end  of  this  section  is  then  to  be  bent 
at  a  right  angle,  flatwise.  This  angle  piece  will  be  long 
enough  if  only  3-16  inch  long,  so  that  it  covers  the  thick- 
ness of  the  zinc  center  rod.  The  zinc  center  rod  is  a  bar  of 
the.  metal,  hammered  or  rolled,  25  inches  long,  3-16  inch 
thick,  and  ^  inch  wide,  and  comes  up  against  the  angle 
piece  bent  on  the  flat  part  of  the  lower  section  of  the  rod. 
Now  the  upper  section  of  the  rod  may  be  an  exact  duplicate 
of  the  lower  section,  with  the  flat  part  only  a  little  longer 
than  the  zinc  bar,  say  Yz  inch,  and  the  angle  turned  on  the 
end,  as  j)reviously  described.  The  balance  of  the  bar  may 
be  forged  into  a  rod  of  5-16  inch  diameter.  As  has  been 
stated, "the  zinc  bar  is  placed  against  the  angle  piece  bent 
on  the  upper  end  of  the  lower  section  of  the  rod,  P,  n.  Fig. 
9,  and  pins  must  be  put  through  this  angle  piece  into  the 
end  of  the  zinc  bar,  to  hold  it  in  close  contact  with  the  iron 
bar.  The  upper  section  of  the  rod  is  now  to  be  laid  on  the 
opposite  side  of  the  zinc  bar,  with  its  angle  at  the  other  end 
of  the  zinc,  but  not  in  contact  with  it,  say  1-16  inch  left 
between  the  angle  and  the  zinc  bar.  Now  all  is  ready  to 
clamp  together — the  two  flat  iron  bars  with  the  zinc  between 
them.  After  clamping,  taking  care  to  have  the  pinned  end 
of  the  zinc  in  contact  with  the  angle  and  the  free,  or  lower 
end,  removed  from  the  other  angle  about  1-16  inch,  three 
screws   should  be  put  through   all  three  bars,   with   their 


44  THE    MODERN    CLOCK. 

heads  all  on  the  side  selected  for  the  front,  and  one  screw 
may  be  an  inch  from  the  top,  another  3  inches  from  the 
bottom,  and  one-half  way  between  the  two  first  mentioned. 
Now  the  rod  is  complete  in  its  composite  form,  and  there 
is  left  only  the  little  detail  to  attend  to.  Two  flat  bars,  with 
their  ends  angled  in  one  case  and  rounded  in  the  other  into 
rods  of  given  diameter,  confining  between  them,  as  de- 
scribed, a  flat  bar  of  wrought  zinc  of  stated  length  and  of 
the  same  thickness  and  width  as  the  iron  bars,  comprises 
the  active  or  compensating  elements  of  the  pendulum's  rod. 
The  screws  that  are  put  through  the  three  bars  are  each  to 
pass  through  the  front  iron  bar,  without  threads  in  the  bar, 
and  only  the  back  iron  bar  is  to  have  the  holes  tapped, 
fitting  the  screws.  All  the  corresponding  holes  in  the  zinc 
are  to  be  reamed  a  little  larger  than  the  diameter  of  the 
screws,  and  to  be  freed  lengthwise  of  the  bar,  to  allow  of 
the  bar's  contracting  and  expanding  without  being  con- 
fined in  this  action  by  the  screws.  At  the  lower  or  free  end 
of  the  zinc  bar  are  to  be  holes  carried  clear  through  all  three 
bars,  while  the  combination  is  held  firmly  together  by  the 
screws.  These  holes  are  to  start  at  ^  inch  from  the  end 
of  the  zinc,  and  each  carried  straight  through  all  three  bars, 
and  then  broached  true  and  a  steel  pin  made  to  accurately 
fit  them  from  the  front  side.  These  holes  may  be  from 
three  to  five  in  number,  extending  up  to  a  safe  distance  from 
the  lower  screw.  The  holes  in  the  back  bar,  after  boring, 
are  to  be  reamed  larger  than  those  in  the  front  bar  and  zinc 
bar.  These  holes  and  the  pin  serve  for  adjusting  the  com- 
pensation. The  pin  holds  the  front  bar  and  zinc  from  slip- 
ping, or  moving  past  one  another  at  the  point  pinned,  and 
also  allows  the  back  bar  to  be  free  of  the  pin,  and  not  under 
the  inflyence  of  the  two  front  bars.  The  upper  end  of  the 
second  iron  section  is,  as  has  been  mentioned,  forged  into 
a  round  rod  about  5-16  inch  diameter,  and  this  rod  or 
upper  end  is  to  receive  the  pendulum  suspension  spring, 
which  may  be  one  single  spring,  or  a  compound  spring, 
as  preferred. 


THE    MODERN    CLOCK.  45 

Now  that  the  pendulum  is  all  ready  to  balance  on  the 
knife  edge,  proceed  as  in  case  of  the  simple  pendulum, 
and  ascertain  at  what  point  up  the  rod  the  spring  must  be 
placed.  In  this  pendulum  the  rod  will  be  heavier  in  propor- 
tion than  the  wood  rod  was  to  its  bob,  and  the  center  of 
gravity  of  the  whole  will  be  found  higher  up  in  the  bob. 
However,  wherever  in  the  bob  the  center  of  gravity  is 
found,  that  is  the  starting  point  to  measure  from  to  find  the 
total  length  of  the  rod,  and  the  point  for  the  spring.  The 
heavier  the  rod  is  in  relation  to  the  bob,  the  higher  will  the 
center  of  gravity  of  the  whole  rise  in  the  bob,  and  the 
greater  will  be  the  total  length  of  the  entire  pendulum. 

In  getting  up  a  rod  of  the  kind  just  described,  the  main 
item  is  to  get  the  parts  all  so  arranged  that  there  will  be 
very  little  settling  of  the  joints  in  contact,  particularly  those 
which  sustain  the  weight  of  the  bob  and  the  whole  dead 
weight  of  the  pendulum.  The  nut  in  the  center  of  the 
pendulum  holds  the  weight  of  the  bob  only,  but  it  should 
fit  against  the  shoulder  formed  for  the  purpose  by  the 
juncture  of  the  two  holes,  and  the  face  of  the  nut  should  be 
turned  true  and  flat,  so  that  there  may  not  be  any  uneven 
motion,  and  only  the  one  imparted  by  the  progressive  one 
of  the  threads.  When  this  nut  is  put  to  its  place  for  the 
last  time,  and  after  all  is  finished,  there  should  be  a  little 
tallow  put  on  to  the  face  of  the  nut  just  where  it  comes 
to  a  seat  against  the  shoulder  of  the  bob,  as  this  shoulder 
being  not  very  well  finished,  the  two  surfaces  coming  in 
contact,  if  left  dry,  might  cut  and  tear  each  other,  and  help 
to  make  the  nut's  action  slightly  unsteady  and  unreliable. 
A  finished  washer  can  be  driven  into  this  lower  hole  up  to 
the  center,  friction  tight,  and  serve  as  a  reliable  and  finished 
seat  for  the  nut. 

In  reality,  the  zinc  at  the  point  of  contact,  where  pinned  to 
the  angle  piece  at  the  top  of  the  lower  section,  is  the  point 
of  greatest  importance  in  the  whole  combination,  and  if  the 
joint  between  the  angle  and  the  end  of  the  zinc  bar  is 


46  THE    MODERN    CLOCK. 

soldered  with  soft  solder,  the  result  will  be  that  of  greater 
certainty  in  the  maintenance  of  a  steady  rate.  This  joint 
just  mentioned  can  be  soldered  as  follows:  File  the  end 
of  the  zinc  and  the  inside  surface  of  the  angle  until  they  fit 
so  that  no  appreciable  space  is  left  between  them.  Then, 
with  a  soldering  iron,  tin  the  end  of  the  zinc  thoroughly 
and  evenly,  and  then  put  into  the  holes  already  made  the 
two  steady  pins.  Now  tin  in  the  same  manner  the  surface 
of  the  angle,  and  see  that  the  holes  are  free  of  solder,  so  that 
the  zinc  bar  will  go  to  its  place  easily ;  then  between  the 
zinc  and  the  iron,  place  a  piece  of  thin  writing  paper,  so 
that  the  flat  surfaces  of  the  zinc  and  iron  may  not  become 
soldered.  Set  the  iron  bar  upright  on  a  piece  of  charcoal, 
and  secure  it  in  this  position  from  any  danger  of  falling, 
and  then  put  the  zinc  to  its  place  and  see  that  the  pins  enter 
and  that  the  paper  is  between  the  surfaces,  as  described. 
Put  the  screws  into  their  places,  and  screw  down  on  the 
zinc  just  enough  to  hold  it  in  contact  with  the  iron  bar,  but 
not  so  tight  that  the  zinc  will  not  readily  move  down  and 
rest  firmly  on  the  angle.  Put  a  little  soldering  fluid  on  the 
tinned  joint,  and  blow  with  a  blow  pipe  against  the  iron- 
bar  (not  touching  the  zinc  with  the  flame).  When  the 
solder  in  the  joint  begins  to  flow,  press  the  zinc  down  in 
close  contact  with  the  angle,  and  then  cool  gradually,  and  if 
all  the  points  described  have  been  attended  to  the  joint  will 
be  solidly  soldered,  and  the  two  bars  will  be  as  one  solid 
bar  bent  against  itself.  The  tinning  leaves  surplus  solder  on 
the  surfaces  suflicient  to  make  a  solid  joint,  and  to  allow 
some  to  flow  into  the  pin  holes  and  also  solder  the  pin  to 
avoid  any  danger  of  getting  loose  in  after  time,  and  helps 
make  a  much  stronger  joint.  At  the  time  the  solder  is 
melted  the  zinc  is  sufliciently  heated  to  become  quite  mal- 
leable, and  care  must  be  taken  not  to  force  it  down  against 
the  angle  in  making  the  joint,  or  it  may  be  distorted  and 
ruined  at  the  joint.  If  carefully  done  the  result  will  be 
perfect.    The  paper  between  the  surfaces  burns,  and  is  got 


THE    MODERN    CLOCK.  47 

rid  of  in  washing  to  remove  the  soldering  fluid.  Soda  or 
ammonia  will  help  to  remove  all  traces  of  the  fluid.  How- 
ever, it  is  best,  as  a  last  operation,  to  put  the  joint  in  alcohol 
for  a  minute. 

This  soldering  makes  the  lower  section  and  the  zinc 
practically  one  piece  and  without  loose  joint,  and  the  next 
joint  is  that  made  by  the  pin  pinning  the  outside  bar  and  the 
zinc  together.  This  is  necessarily  formed  this  way,  as  in 
this  stage  of  the  operation  we  do  not  know  just  what  length 
the  zinc  bar  will  be  to  exactly  compensate  for  the  expansion 
and  contraction  of  the  balance  of  the  pendulum.  By  the 
changing  of  the  pin  into  the  different  holes,  5,  6,  7,  8,  9,  10, 
Fig.  9,  the  zinc  is  made  relatively  longer  or  shorter,  and  so 
a  compensation  is  arrived  at  in  time  after  the  clock  has  been 
running.  After  it  is  definitely  settled  where  the  pin  will 
remain  to  secure  the  compensation  of  the  rod,  then  that 
hole  can  have  a  screw  put  in  to  match  the  three  upper  ones. 
This  screw  must  be  tapped  into  the  front  bar  and  the  zinc, 
and  be  very  free  in  the  back  bar  to  allow  of  its  expansion. 
It  is  supposed  that  in  this  example  given  of  a  zinc  and  steel 
compensation  seconds  pendulum  that  there  has  been  due 
allowance  made  in  the  lengths  of  the  several  bars  to  allow 
for  adjustment  to  temperature  by  the  movements  of  the  pin 
along  the  course  of  the  several  holes  described,  but  the  zinc 
is  a  very  uncertain  element,  and  its  ultimate  action  is  largely 
influenced  by  its  treatment  after  being  cast.  Differences  of 
working  cast  zinc  under  the  hammer  or  rolls  produce  wide 
differences  practically,  and  therefore  materially  change  the 
results  in  its  combination  with,  iron  in  their  relative  ex- 
pansive action.  Wrought  zinc  can  be  obtained  of  any  of  the 
brass  plate  factories,  of  any  dirriensions  required,  and  will 
be  found  to  be  satisfactory  for  the  purpose  in  hand. 

The  adjusting  pin  should  be  well  fitted  to  the  holes  in  the 
front  iron  bar,  and  also  fit  the  corresponding  ones  in  the 
zinc  bar  closely,  and  if  the  holes  are  reamed  smooth  and 
true  with  an  English  clock  broach,  then  the  pin  will  be 


48  THE    MODERN    CLOCK. 

slightly  tapering  and  fit  the  iron  hole  perfectly  solid.  After 
one  pair  of  these  holes  have  been  reamed,  fit  the  pin  and 
drive  it  in  place  perfectly  firm,  and  then  with  the  broach 
ream  all  the  remaining  holes  to  just  the  same  diameter, 
and  then  the  pin  will  move  along  from  one  set  of  holes  to 
another  with  mechanically  accurate  results.  Otherwise,  if 
poorly  fitted,  the  full  effect  would  not  be  obtained  from  the 
compensating  action  in  making  changes  in  the  pin  from 
one  set  of  holes  to  another.  This  pin,  if  made  of  cast  steel, 
hardened  and  drawn  to  a  blue,  will  on  the  whole  be  a  very 
good  device  mechanically. 

Many  means  are  used  to  effect  the  adjustments  for  com- 
pensation, of  more  or  less  value,  but  whatever  the  means 
used,  it  must  be  kept  in  mind  that  extra  care  must  be  taken 
to  have  the  mechanical  execution  first  class,  as  on  this  very 
much  depends  the  steady  rate  of  the  pendulum  in  after 
time. 

Tubular  Compensated  Rods. — There  are  tubular  pendu- 
lums in  the  market  which  have  a  screw  sleeve  at  the  top  of 
the  zinc  element,  and  by  this  means  the  adjustments  are 
effected,  and  this  is  thought  to  be  a  very  accurate  mechan- 
ism. The  most  common  form  of  zinc  and  iron  compensa- 
tion is  where  the  zinc  is  a  tube  combined  with  one  iron  tube 
and  a  central  rod,  as  shown  in  Figs.  lo,  ii,  12.  The  rod 
is  the  center  piece,  the  zinc  tube  next,  followed  by  the  iron 
tube  enveloping  both.  The  relative  lengths  may  be  the 
same  as  those  just  given  in  the  foregoing  example  with  the 
compensating  elements  flat.  The  relative  lengths  of  the 
several  members  will  be  virtually  the  same  in  both  com- 
binations. 

Tubular  Compensation  with  Aluminum. — The  pen- 
dulum as  seen  by  an  observer  appears  to  him  as  being  a 
simple  single  rod  pendulum.  Figs.  10  and  12  are  front 
and  side  views ;   Fig.  1 1  is  an  enlarged  view  of  its  parts,  the 


THE    MODERN    CLOCK, 


49 


upper  being  a  sectional  view.  Its  principal  features  are: 
The  steel  rod  S,  Fig.  ii,  4  mm.  in  diameter,  having  at  its 
upper  end  a  hook  for  fastening  to  the  suspension  spring  in 
the  usual  way ;  the  lower  end  has  a  pivot  carrying  the  bush- 
ing, T,  which  solidly  connects  the  steel  rod,  S,  with  the 
aluminum  tube.  A,  the  latter  being  10  mm.  in  diameter  and 
its  sides  1.5  mm.  in  thickness  of  the  wall. 

The  upper  end  of  the  aluminum  tube  is  very  close  to  the 
pendulum  hook  and  is  also  provided  with  a  bushing,  P, 
Fig.  II.  This  bushing  is  permanently  connected  at  the 
upper  end  of  the  aluminum  tube  with  a  steel  tube,  R,  16  mm. 
in  diameter  and  i  mm.  in  thickness.  The  outer  steel  tube 
is  the  only  one  that  is  visible  and  it  supports  the  bob,  the 
lower  part  being  furnished  with  a  fine  thread  on  which 
the  regulating  nut,  O,  is  movable,  at  the  center  of  the  bob. 

For  securing  a  central  alignment  of  the  steel  rod,  S,  at  its 
lowest  part,  where  it  is  pivoted,  a  bushing,  M,  Fig.  11,  is 
screwed  into  the  steel  tube,  R.  The  lower  end  of  the  steel 
tube,  R,  projects  considerably  below  the  lenticular  bob 
(compare  Figs.  10  and  12)  ;  and  is  also  provided  with  a 
thread  and  regulating  weight,  G  (Figs.  10  and  12),  of  100 
grammes  in  weight,  which  is  only  used  in  the  fine  regula- 
tion of  small  variations  from  correct  time. 

The  steel  tube  is  open  at  the  bottom  and  the  index  at  its 
lower  end  is  fastened  to  a  bridge.  Furthermore  all  three 
of  the  bushings,  P,  T  and  M,  have  each  three  radial  cuts, 
which  will  permit  the  surrounding  air  to  act  equally  and  at 
the  same  time  on  the  steel  rod,  S,  the  aluminum  tube.  A,  and 
the  steel  tube,  R,  and  as  the  steel  tube,  R,  is  open  at  its 
lower  end,  and  as  there  is  also  a  certain  amount  of  space  be- 
tween the  tubes,  the  steel  rod,  and  the  radial  openings  in 
the  bushings,  there  will  be  a  draught  of  air  passing  through 
them,  which  will  allow  the  thin- walled  tubes  and  thin  steel 
rod  to  promptly  and  equally  adapt  themselves  to  the  temper- 
ature of  the  air. 


Fig.  10. 


Fig.  U. 


Fig.  12. 


THE    MODERN    CLOCK.  5I 

The  lenticular  pendulum  bob  has  a  diameter  of  24  cm., 
and  is  made  of  red  brass.  The  bob  is  supported  at  its  cen- 
ter by  the  regulating  nut,  O,  Figs.  10  and  12.  That  the 
bob  may  not  turn  on  the  cylindrical  pendulum  rod,  the  latter 
is  provided  with  a  longitudinal  groove  and  working  therein 
are  the  ends  of  two  shoulder  screws  which  are  placed  on 
the  back  of  the  bob  above  and  below  the  regulating  nut,  O ; 
and  thus  properly  controlling  its  movements. 

From  the  foregoing  description  the  action  of  the  compen- 
sation is  readily  explained.  For  the  purpose  of  illustration 
of  its  action  we  will  accept  the  fact  that  there  has  been  a 
sudden  rise  in  temperature.  The  steel  rod,  S,  and  the  tube, 
R,  will  lengthen  in  a  downward  direction  (including  the 
suspension  spring  and  the  pendulum  hook),  conversely  the 
aluminum  tube.  A,  which  is  fastened  to  the  steel  rod  at  one 
end  and  the  steel  tube  at  the  other,  will  lengthen  in  an 
upward  direction  and  thus  equalize  the  expansion  of  the 
tube,  R,  and  rod,  S. 

As  the  coefficients  of  expansion  of  steel  and  aluminum  are 
approximately  at  the  ratio  of  1 12.0313  we  find  that  with  such 
a  pendulum  construction — accurate  calculations  presumed 
— we  shall  have  a  complete  and  exact  coincidence  in  its 
compensation ;  in  other  words,  the  center  of  oscillation  of 
the  pendulum  will  be  under  all  conditions  at  the  same  dis- 
tance from  the  bending  point  of  the  suspension  spring. 

This  style  of  pendulum  is  made  for  astronomical  clocks  in 
Europe  and  is  furnished  in  two  qualities.  In  the  best  qual- 
ity, the  tubes,  steel  rod,  and  the  bob  are  all  separately  and 
carefully  tested  as  to  their  expansion,  and  their  coefficients 
of  expansion  fully  determined  in  a  laboratory ;  the  bush- 
ings, P  and  M,  are  jeweled,  all  parts  being  accurately  and 
finely  finished.  In  the  second  quality  the  pendulum  is  con- 
structed on  a  general  calculation  and  finished  in  a  more 
simple  manner  without  impairing  its  ultimate  efficiency. 

At  the  upper  part  of  the  steel  tube,  R,  there  is  a  funnel- 
shaped  piece  (omitted  in  the  drawing)  in  which  are  placed 


52  THE    MODERN    CLOCK. 

small  lead  and  aluminum  balls  for  the  final  regulation  of  the 
pendulum  without  stopping  it. 

The  regulation  of  this  pendulum  is  effected  in  three 
ways : 

I.  The  preliminary  or  coarse  regulation  by  turning  the 
regulating  nut,  O,  and  so  raising  or  lowering  the  bob. 
2.  The  finer  regulation  by  turning  the  lOO  grammes 
weight,  g,  having  the  shape  of  a  nut  and  turning  on  the 
threaded  part  of  the  tube,  R.  3.  The  precision  regulation 
is  effected  by  placing  small  lead  or  aluminum  balls  in  a 
small  funnel-shaped  receptacle  attached  to  the  upper  part 
of  the  tube,  R,  or  by  removing  them  therefrom. 

It  will  readily  be  seen  that  this  form  of  pendulum  can  be 
used  with  zinc  or  brass  instead  of  aluminum,  by  altering  the 
lengths  of  the  inner  rod  and  the  compensating  tube  to  suit 
the  expansion  of  the  metal  it  is  decided  to  use ;  also  that 
alterations  in  length  may  be  made  by  screwing  the  bushings 
in  or  out,  provided  that  the  tube  be  long  enough  in  the 
first  place.  After  securing  the  right  position  the  bushings 
should  have  pins  driven  into  them  through  the  tube,  in  order 
'to  prevent  further  shifting. 


CHAPTER  IV. 

THE   CONSTRUCTION    OF    MERCURIAL   PENDULUMS. 

Owing  to  the  difficulty  of  calculating  the  expansive  ratios 
of  metal  which  (particularly  with  brass  and  zinc)  vary 
slightly  with  differences  of  manufacture,  the  manufacture 
of  compensated  pendulums  from  metal  rods  cannot  be  re- 
duced to  cutting  up  so  many  pieces  and  assembling  them 
from  calculations  made  previously,  so  that  each  must  be 
separately  built  and  tested.  While  this  is  not  a  great  draw- 
back to  the  jeweler  who  wants  to  make  himself  a  pendu- 
lum, it  becomes  a  serious  difficulty  to  a  manufacturer,  and 
hence  a  cheaper  combination  had  to  be  devised  to  prevent 
the  cost  of  compensated  pendulums  from  seriously  inter- 
fering with  their  use.  The  result  was  the  pendulum  com- 
posed of  a  steel  rod  and  a  quantity  of  mercury,  the  latter 
forming  the  principal  weight  for  the  bob  and  being  con- 
tained in  steel  or  glass  jars,  or  jars  of  cast  iron  for  the 
heavier  pendulums.  Other  metals  will  not  serve  the  pur- 
pose, as  they  are  corroded  by  the  mercury,  become  rotten 
and  lose  their  contents. 

Mercury  has  one  deficiency  which,  however,  is  not  seri- 
ous, except  for  the  severe  conditions  of  astronomical  obser- 
vatories. It  will  oxidize  after  long  exposure  to  the  air, 
when  it  must  be  strained  and  a  fresh  quantity  of  metal 
added  and  the  compensation  freshly  adjusted.  To  an  as- 
tronomer this  is  a  serious  objection,  as  it  may  interfere  with 
his  work  for  a  month,  but  to  the  jeweler  this  is  of  little 
moment  as  the  rates  he  demands  will  not  be  seriously  affect- 
ed for  about  ten  years,  if  the  jars  are  tightly  covered. 

To  construct  a  reliable  gridiron  pendulum  would  cost 
about  fifty  dollars  while  a  mercurial  pendulum  can  be  well 
made  and  compensated  for  about  twenty-five  dollars,  hence 
the  popularity  of  the  latter  form. 

53 


54;       '  THE     MODERN     CLOCK, 

Zinc  will  lengthen  under  severe  variations  of  tempera- 
ture as  the  following  will  show:  Zinc  has  a  decided  objec- 
tionable quality  in  its  crystalline  structure  that  with  temper- 
ature changes  there  is  very  unequal  expansion  and  con- 
traction, and  furthermore,  that  these  changes  occur  sud- 
deiily;  this  often  results  in  the  bending  of  the  zinc  rod,, 
causing  a  binding  to  take  place,  which  naturally  enough 
prevents  the  correct  working  of  the  compensation. 

It  is  probably  not  very  well  known  that  zinc  can  change 
its  length  at  one  and  the  same  temperature,  and  that  this 
peculiar  quality  must  not  be  overlooked.  The  U.  S.  Lake 
Survey,  which  has  under  its  charge  the  triangulation  of  the 
great  lakes  of  the  United  States,  has  in  its  possession  a  steel 
meter  measure,  R,  1876;  a  metallic  thermometer  composed 
of  a  steel  and  zinc  rod,  each  being  one  meter  in  length,, 
marked  M.  T.,  1876s,  and  M.  T.  1876Z;  and  four  metallic 
thermometers,  used  in  connection  with  the  base  apparatus, 
which  likewise  are  made  of  steel  and  zinc  rods,  each  of 
these  being  four  meters  in  length.  All  of  these  rods  were 
made  by  Repsold,  of  Hamburg.  Comparisons  between  these 
different  rods  show  peculiar  variations,  and  which  point  to 
the  fact  that  their  lengths  at  the  same  degree  of  temperature 
are  not  constant.  For  the  purpose  of  determining  these 
variations  accurate  investigations  were  undertaken.  The 
metallic  thermometer  M.  T.  1876  was  removed  from  an  ob- 
servatory room  having  an  equal  temperature  of  about  2°  C. 
and  placed  for  one  day  in  a  temperature  of  4-24°  C,  and 
also  for  the  same  period  of  time  in  one  of  — 20°  C ;  it  was 
then  replaced  in  the  observatory  room,  where  it  remained 
for  twenty-four  hours,  and  comparisons  were  made  during 
the  following  three  days  with  the  steel  thermometer  R, 
1876,  which  had  been  left  in  the  room.  From  these  obser- 
vations and  comparisons  the  following  results  were  tabu- 
lated, which  give  the  mean  leng^ths  of  the  zinc  rods  of  the 
metallic  thermometer.  The  slight  variations  of  temperature 
in  the  observatory  room  were  also  taken  into  consideration 
in  the  calculations : 


MODERN     CLOCK.        ^^^'    ^^^SgS 


M.  T.  1876s.        M.  T.  1876Z. 
mm.  mm. 

Februar}^  16-24  —  0.0006  +  0.0152,  previous  7  days  at  +  24°C 

February  25-27  —  0.0017  —  o.ooii,  previous  i  day    at  —  20°C 

March         2-4    +  0.0005  +  0.0154,  previous  i  day     at  +  24° C. 

March         5-8   — 0.0058  —  0.0022,  previous  i  day    at  —  20° C. 

These  investigations  clearly  indicate,  without  doubt,  that 
the  zinc  rod  at  one  and  the  same  temperature  of  about  2°  C, 
is  0.018  mm.  longer  after  having  been  previously  heated  to 
24°  C.  than  when  cooled  before  to  — 20°  C. 

A  similar  but  less  complete  examination  was  made  with 
the  metallic  thermometer  four  meters  in  length.  These 
trials  were  made  by  that  efficient  officer,  General  Corn- 
stock,  gave  the  same  results,  and  completely  prove  that  in 
zinc  there  are  considerable  thermal  after-effects  at  work. 

To  prove  that  zinc  is  not  an  efficient  metal  for  compensa- 
tion pendulums  when  employed  for  the  exact  measurement 
of  time,  a  short  calculation  may  be  made — using  the  above 
conclusions — that  a  zinc  rod  one  meter  in  length,  after 
being  subjected  to  a  difference  of  temperature  of  44  C.  will 
alter  its  length  0.018  mm.  after  having  been  brought  back 
to  its  initial  degree.  For  a  seconds  pendulum  with  zinc 
compensation  each  of  the  zinc  rods  would  require  a  length 
of  64.9  cm.  With  the  above  computations  we  get  a  differ- 
ence in  length  of  0.0117  mm.  at  the  same  degree  of  temper- 
ature. Since  a  lengthening  of  the  zinc  rods  without  a  suit- 
able and  contemporaneous  expansion  of  the  steel  rods  is 
synonymous  with  a  shortening  of  the  effectual  pendulum 
length,  we  have,  notwithstanding  the  compensation,  a  short- 
ening of  the  pendulum  length  of  0.017  mm.,  which  corre- 
sponds to  a  change  in  the  daily  rate  of  about  0.5  seconds. 

This  will  sufficiently  prove  that  zinc  is  unquestionably 
not  suitable  for  extremely  accurate  compensation  pendu- 
lums, and  as  neither  is  permanent  under  extremes  of  tem- 
perature the  advantages  of  first  cost  and  of  correction  of 
error  appear  to  lie  with  the  mercurial  form. 


56  THE     MODERN     CLOCK. 

The  average  mercurial  compensation  pendulums,  on  sale 
in  the  trade  are  often  only  partially  compensated,  as  the 
mercury  is  nearly  always  deficient  in  quantity  relatively, 
and  not  high  enough  in  the  jar  to  neutralize  the  action  of 
the  rigid  metallic  elements,  composing  the  structure.  The 
trouble  generally  is  that  the  mercury  forms  too  small  a  pro- 
portion of  the  total  weight  of  the  pendulum  bob.  There 
is  a  fundamental  principle  governing  these  compensating 
pendulums  that  has  to  be  kept  in  mind,  and  that  is  that  one 
of  the  compensating  elements  is  expected  to  just  undo  what 
the  other  does  and  so  establish  through  the  medium  of 
physical  things  the  condition  of  the  ideal  pendulum,  with- 
out weight  or  elements  outside  of  the  bob.  As  iron  and 
mercury,  for  instance,  have  a  pretty  fixed  relative  expansive 
ratio,  then  whatever  these  ratios  are  after  being  found,  must 
be  maintained  in  the  construction  of  the  pendulum,  or  the 
results  cannot  be  satisfactory. 

First,  there  are  39.2  inches  of  rod  of  steel  to  hold  the 
bob  between  the  point  of  suspension  and  the  center  of  oscil- 
lation, and  it  has  been  found  that,  constructively,  in  all 
the  ordinary  forms  of  these  pendulums,  the  height  of  mer- 
cury in  the  bob  cannot  usually  be  less  than  7.5  inches.  Sec- 
ond, that  in  all  seconds  pendulums  the  length  of  the  metal 
is  fixed  substantially,  while  the  height  of  the  mercury  is  a 
varying  one,  due  to  the  differing  weights  of  the  jars, 
straps,  etc. 

Third,  the  mercury,  at  its  minimum,  cannot  with  jars  of 
ordinary  weight  be  less  in  height  in  the  jar  than  7.5  inches, 
to  effectually  counteract  what  the  39.2  inches  of  iron  does 
in  the  way  of  expanding  and  contracting  under  the  same 
exposure. 

Whoever  observes  the  great  mass  of  pendulums  of  this 
description  on  sale  and  in  use  will  find  that  the  height 
of  the  mercury  in  the  jar  is  not  up  to  the  amount  given 
above  for  the  least  quantity  that  will  serve  under  the  most 
favorable  circumstances  of  construction.     The  less  weight 


THE     MODERN     CLOCK.  57 

there  is  in  the  rod,  jar  and  frame,  the  less  is  the  height 
of  mercury  which  is  required ;  but  with  most  of  the  pendu- 
lums made  in  the  present  day  for  the  market,  the  height 
given  cannot  be  cut  short  without  impairing  the  quality  and 
efficiency  of  the  compensation.  Any  amount  less  will  have 
the  effect  of  leaving  the  rigid  metal  in  the  ascendancy ;  or, 
in  other  words,  the  pendulum  will  be  under  compensated 
and  leave  the  pendulum  to  feel  heat  and  cold  by  raising  and 
lowering  the .  center  of  oscillation  of  the  pendulum  and 
hence  only  partly  compensating.  A  jar  with  only  six  inches 
in  height  of  mercury  will  in  round  numbers  only  correct  the 
temperature  error  about  six-sevenths. 

Calculations  of  Weights. — As  to  how  to  calculate  the 
amount  of  mercury  required  to  compensate  a  seconds  pendu- 
lum, the  following  explanation  should  make  the  matter 
clear  to  anyone  having  a  fair  knowledge  of  arithmetic  only, 
though  there  are  several  points  to  be  considered  which 
render  it  a  rather  more  complicated  process  than  would  ap- 
pear at  first  sight. 

1st.  The  expansion  in  length  of  steel  and  cast  iron,  as 
given  in  the  tables  (these  tables  differ  somewhat  in  the 
various  books),  is  respectively  .0064  and  .0066,  while  mer- 
cury expands  .1  in  bulk  for  the  same  increase  of  tempera- 
ture. If  the  mercury  were  contained  in  a  jar  which  itself 
had  no  expansion  in  diameter,  then  all  its  expansion  would 
take  place  in  height,  and  in  round  numbers  it  would  expand 
sixteen  times  more  than  steel,  and  we  should  only  require 
(neglecting  at  present  the  allowance  to  be  explained  under 
head  3)  to  make  the  height  of  the  mercury — reckoned  from 
the  bottom  of  the  jar  (inside)  to  the  middle  of  the  column 
of  mercury  contained  therein — one-sixteenth  of  the  total 
length  of  the  pendulum  measured  from  the  point  of  sus- 
pension to  the  bottom  of  the  jar,  assuming  that  the  rod  and 
the  jar  are  both  of  steel,  and  that  the  center  of  oscillation 
is  coincident  with  the   center  of  the  column  of  mercury. 


JS  THE     MODERN     CLOCK. 

Practically  in  these  pendulums,  the  center  of  oscillation 
is  almost  identical  with  the  center  of  the  bob. 

2d.  As  we  cannot  obtain  a  jar  having  no  expansion  in 
diameter,  we  must  allow  for  such  expansion  as  follows,, 
and  as  cast-iron  or  steel  jars  of  cylindrical  shape  are  un- 
doubtedly the  best,  we  will  consider  that  material  and  form 
only. 

As  above  stated,  cast  iron  expands  .0066,  so  that  if  the 
original  diameter  of  the  jar  be  represented  by  i,  its  ex- 
panded diameter  will  be  1.0066.  Now  the  area  of  any  circle 
varies  as  the  square  of  its  diameter,  so  that  before  and  after 
its  expansion  the  areas  of  the  jar  will  be  in  the  ratio  of  i^ 
to  1.0066^;  that  is,  in  the  proportion  of  i  to  i. 01 3243;  or 
in  round  numbers  it  will  be  one-seventy-sixth  larger  in  area 
after  expansion  than  before.  It  is  evident  that  the  mercury 
will  then  expand  sideways,  and  that  its  vertical  rise  will  be 
diminished  to  the  same  extent.  Deduct,  therefore,  the  one- 
seventy-sixth  from  its  expansion  in  bulk  (one-tenth)  and  we 
get  one-eleventh  (or  more  exactly  .086757)  remaining. 
This,  then,  is  the  actual  vertical  rise  in  the  jar,  and  when 
compared  with  the  expansion  of  steel  in  length  it  will  be 
found  to  be  about  thirteen  and  a  half  tim.es  greater  (more 
exactly  13-556). 

The  mercury,  therefore  (still  neglecting  head  No.  3)^ 
must  be  thirteen  and  a  half  times  shorter  than  the  length 
of  the  pendulum,  both  being  measured  as  explained  above. 
The  pendulum  will  probably  be  43.5  inches  long  to  the 
bottom  of  the  jar;  but  as  about  nine  inches  of  it  is  cast 
iron,  which  has  a  slightly  greater  rate  of  expansion  than 
steel,  we  will  call  the  length  44  inches,  as  the  half  inch 
added  will  make  it  about  equivalent  to  a  pendulum  entirely 
of  steel.  If  the  height  of  the  mercury  be  obtained  by  di- 
viding 44  by  13.5,  it  will  be  3.25  inches  high  to  its  center, 
or  6.5  inches  high  altogether;  and  were  it  not  for  the  fol- 
lowing circumstance,  the  pendulum  would  be  perfectly 
compensated. 


THE     MODERN     CLOCK.  59 

3d.  The  mercury  is  the  only  part  of  the  bob  which  ex- 
pands upwards;  the  jar  does  not  rise,  its  lower  end  being 
carried  downward  by  the  expansion  of  the  rod,  which  sup- 
ports it.  In  a  well-designed  pendulum,  the  jar,  straps,  etc.;, 
will  be  from  one-fourth  to  one-third  the  weight  of  the  mer- 
cury. Assume  them  to  be  seven  pounds  and  twenty-eight 
pounds  respectively;  therefore,  the  total  weight  of  the  bob 
is  thirty-five  pounds;  but  as  it  is  only  the  mercury  (four- 
fifths)  of  this  total  that  rises  with  an  increase  of  tempera- 
ture, we  must  increase  the  weight  of  the  mercury  in  the 
proportion  of  five  to  four,  thus  6.5  X  5  -r-  4  =  ^H  inches. 
Or,  what  is  the  same  thing,  we  add  one-fourth  to  the 
amount  of  mercury,  because  the  weight  of  the  jar  is  one- 
fourth  of  that  of  the  mercury.  Eight  and  one-eighth 
inches  is,  therefore,  the  ultimate  height  of  the  mercury  re- 
quired to  compensate  the  pendulum  with  that  weight  of  jar. 
If  the  jar  had  been  heavier,  say  one-third  the  weight  of  the 
mercury,  then  the  latter  would  have  to  be  nearly  8.75  inches 
high. 

If  the  jar  be  required  to  be  of  glass,  then  we  substitute 
the  expansion  of  that  material  in  No.  2  and  its  weight  in 
No.  3. 

In  the  above  method  of  calculating,  there  are  two  slight 
elements  of  uncertainty:  ist.  In  assuming  that  the  center 
of  oscillation  is  coincident  with  the  center  of  the  bob ;  how^- 
ever,  I  should  suppose  that  they  would  never  be  more  than 
.25  inch  apart,  and  generally  much  nearer.  2d.  The  weight 
of  the  jar  cannot  well  be  exactly  known  until  after  it  is 
finished  (i.  e.,  bored  smooth  and  parallel  inside,  and  turned 
outside  true  with  the  interior),  so  that  the  exact  height  of 
the  mercury  cannot  be  easily  ascertained  till  then. 

I  may  explain  that  the  reason  (in  Nos.  i  and  2)  we  meas- 
ure the  mercury  from  the  bottom  to  the  center  of  the  col- 
umn, is  that  it  is  its  center  which  we  wish  to  raise  when  an 
increase  of  temperature  occurs,  so  that  the  center  may 
always   be   exactly   the   same   distance   from   the   point   of 


6o  THE     MODERN     CLOCK. 

suspension ;  and  we  have  seen  that  3.25  inches  is  the  neces- 
sary quantity  to  raise  it  sufficiently.  Now  that  center  could 
not  be  the  center  without  it  had  as  much  mercury  over  it  as 
it  has  under  it;  hence  we  double  the  3.25  and  get  the  6.5 
inches  stated. 

'  From  the  foregoing  it  will  be  seen  that  the  average  mer- 
cury pendulums  are  better  than  a  plain  rod,  from  the  fact 
that  the  mercury  is  free  to  obey  the  law  of  expansion,  and 
so,  to  a  certain  degree,  does  counteract  the  action  of  the 
balance  of  the  metal  of  the  pendulum,  and  this  with  a 
degree  of  certainty  that  is  not  found  in  the  gridiron  form, 
provided  always  that  the  height  and  amount  of  the  mer- 
cury are  correctly  proportional  to  the  total  weight  of  the 
pendulum. 

Compensating  Mercurial  Pendulums. — To  compen- 
sate a  pendulum  of  this  kind  takes  time  and  study.  The 
first  thing  to  do  is  to  place  maximum  and  minimum  ther- 
mometers in  the  clock  case,  so  that  you  can  tell  the  tem- 
perature. 

Then  get  the  rate  of  the  clock  at  a  given  temperature. 
For  example,  say  the  clock  gains  two  seconds  in  twenty- 
four  hours,  the  temperature  being  at  70°.  Then  see  how 
much  it  gains  when  the  temperature  is  at  80°.  We  will 
say  it  gains  two  seconds  more  at  80°  than  it  does  when 
the  temperature  is  at  70°. 

In  that  case  we  must  remove  some  of  the  mercury  in 
order  to  compensate  the  pendulum.  To  do  this  take  a 
syringe  and  soak  the  cotton  or  whatever  makes  the  suction 
in  the  syringe  with  vaseline.  The  reason  for  doing  this  is 
that  mercury  is  very  heavy  and  the  syringe  must  be  air 
tight  before  you  can  take  any  of  the  mercury  up  into  it. 

You  want  to  remove  about  two  pennyweights  of  mer- 
cury to  every  second  the  clock  gains  in  twenty-four  hours. 
Now,  after  removing  the  mercury  the  clock  will  lose  time, 
because  the  pendulum  is  lighter.     You  must  then  raise  the 


THE     MODERN     CLOCK.  6l 

ball  to  bring  it  to  time.  You  then  repeat  the  same  opera- 
tion by  getting  the  rate  at  76°  and  80°  again  and  see  if  it 
gains.  When  the  temperature  rises,  if  the  pendulum  still 
gains,  you  must  remove  more  mercury;  but  if  it  should 
lose  time  when  the  temperature  rises  you  have  taken  out 
too  much  mercury  and  you  must  replace  some.  Continue 
this  operation  until  the  pendulum  has  the  same  rate,  wheth- 
er the  temperature  is  high  or  low,  raising  the  bob  when 
you  take  out  mercury  to  bring  it  to  time,  and  lowering  the 
bob  when  you  put  mercury  in  to  bring  it  to  time. 

To  compensate  a  pendulum  takes  time  and  study  of  the 
clock,  but  if  you  follow  out  these  instructions  you  will  suc- 
ceed in  getting  the  clock  to  run  regularly  in  both  summer 
and  winter. 

Besides  the  oxidation,  which  is  an  admitted  fault,  there 
are  two  theoretical  questions  which  have  to  do  with  con- 
struction in  deciding  between  the  metallic  and  mercurial 
forms  of  compensation.  We  will  present  the  claims  of  each 
side,  therefore,  with  the  preliminary  statement  that  (for  all 
except  the  severest  conditions  of  accuracy)  either  form,  if 
well  made  will  answer  every  purpose  and  that  therefore, 
except  in  special  circumstances,  these  objections  are  more 
theoretical  than  real. 

The  advocates  of  metallic  compensation  claim  that  where 
there  are  great  differences  of  temperature,  the  compensated 
rod,  with  its  long  bars  will  answer  more  quickly  to  temper- 
ature changes  as  follows : 

The  mercurial  pendulum,  when  in  an  unheated  room 
and  not  subjected  to  sudden  temperature  changes,  gives 
very  excellent  results,  but  should  the  opposite  case  occur 
there  will  then  be  observed  an  irregularity  in  the  rate  of 
the  clock.  The  causes  which  produce  these  effects  are 
various.  As  a  principal  reason  for  such  a  condition  it  may 
be  stated  that  the  compensating  mercury  occupies  only 
about  one-fifth  the  pendulum  length,  and  it  inevitably  fol- 
lows that  when  the  upper  strata  of  the  air  is  warmer  than 


^2  THE     MODERN     CLOCK. 

the  lower,  in  which  the  mercury  is  placed,  the  steel  pendu- 
lum rod  will  expand  at  a  different  ratio  than  the  mercury, 
as  the  latter  is  influenced  by  a  different  degree  of  tempera- 
ture than  the  upper  part  of  the  pendulum  rod.  The  natural 
effect  will  be  a  lengthening  of  the  pendulum  rod,  notwith- 
standing the  compensation,  and  therefore,  a  loss  of  time  by 
the  clock. 

Two  thermometers,  agreeing  perfectly,  were  placed  in 
the  case  of  a  clock,  one  near  the  point  of  suspension,  and  the 
other  near  the  middle  of  the  ball,  and  repeated  experiments, 
showed  a  difference  between  these  two  thermometers  of  7° 
to  io^°F.,the  lower  one  indicating  less  than  the  higher  one. 
The  thermometers  were  then  hung  in  the  room,  one  at 
twenty-two  inches  above  the  floor,  and  the  other  three  feet 
higher,  when  they  showed  a  difference  of  7°  between  them. 
The  difference  of  2.5°  more  which  was  found  inside  the 
case  proceeds  from  the  heat  striking  the  upper  part  of  the 
case ;  and  the  wood,  though  a  bad  conductor,  gradually  in- 
creases in  temperature,  while,  on  the  contrary,  the  cold 
rises  from  the  floor  and  acts  on  the  lower  part  of  the  case, 
The  same  thermometers  at  the  same  height  and  distance  in 
an  unused  room,  which  was  never  warmed,  showed  no  dif- 
ference between  them ;  and  it  would  be  the  same,  doubtless, 
in  an  observatory. 

From  the  preceding  it  is  very  evident  that  the  decrease  of 
rate  of  the  clock  since  December  13  proceeded  from  the  rod 
of  the  pendulum  experiencing  7°  to  10.5°  F.  greater  heat 
than  the  mercury  in  the  bob,  thus  showing  the  impossibility 
of  making  a  mercurial  pendulum  perfectly  compensating 
in  an  artificially  heated  room  which  varies  greatly  in  tem- 
perature. I  should  remark  here  that  during  the  entire 
winter  the  temperature  in  the  case  is  never  more  than  68° 
F.,  and  during  the  summer,  when  the  rate  of  the  clock  was 
regular,  the  thermometer  in  the  case  has  often  indicated 
72°  to  yy""  F. 

The  gridiron  pendulum  in  this  case  would  seem  prefer- 
able, for  if  the  temperature  is  higher  at  the  top  than  at  the 


THE     MODERN     CLOCK.  63 

lower  part,  the  nine  compensating  rods  are  equally  effected 
by  it.  But  in  its  compensating  action  it  is  not  nearly  as 
regular,  and  it  is  very  difficult  to  regulate  it,  for  in  any 
room  (artificially  heated)  it  is  impossible  to  obtain  a  uni- 
form temperature  throughout  its  entire  length,  and  with- 
out that  all  proofs  are  necessarily  inexact. 

These  facts  can  also  be  applied  to  pendulums  situated  in 
heated  rooms.  In  the  case  of  a  rapid  change  in  tempera- 
ture taking  place  in  the  observatory  rooms,  under  the  domes 
of  observatories,  especially  during  the  winter  months,  and 
which  are  of  frequent  occurrence,  a  mercurial  compensa- 
tion pendulum,  as  generally  made,  is  not  apt  to  give  a  re- 
liable rate.  Let  us  accept  the  fact,  as  an  example,  of  a 
considerable  fall  in  the  temperature  of  the  surrounding  air ; 
the  thin,  pendulum  rod  will  quickly  accept  the  same  tempera- 
ture, but  with  the  great  mass  of  mercury  to  be  acted  upon 
the  responsive  effects  will  only  occur  after  a  considerable 
lapse  of  time.  The  result  will  be  a  shortening  of  the  pendu- 
lum length  and  a  gain  in  the  rate  until  the  mercury  has 
had  time  to  respond,  notwithstanding  the  compensation. 

Others  who  have  expressed  their  views  in  writing  seem 
to  favor  the  idea  that  this  inequality  in  the  temperature  of 
the  atmosphere  is  unfavorable  to  the  accurate  action  of  the 
mercurial  form  of  compensation;  and  however  plausible 
and  reasonable  this  idea  ma}^  seem  at  first  notice,  it  will  not 
take  a  great  amount  of  investigation  to  show  that,  instead 
of  being  a  disadvantage,  its  existence  is  beneficial,  and  an 
important  element  in  the  success  of  mercurial  pendulums. 

It  appears  that  the  majority  of  those  who  have  proposed, 
or  have  tried  to  improve  Graham's  pendulum  have  over- 
looked the  fact  that  different  substances  require  different 
quantities  of  heat  to  raise  them  to  the  same  temperature.  In 
order  to  warm  a  certain  weight  of  water,  for  instance, 
to  the  same  degree  of  heat  as  an  equal  weight  of  oil,  or  an 
equal  weight  of  mercury,  twice  as  much  heat  must  be  given 
to  the  water  as  to  the  oil,  and  thirty  times  as  much  as  to  the 


64  THE     MODERN     CLOCK. 

mercury ;  while  in  cooling  down  again  to  a  given  tempera- 
ture, the  oil  will  cool  twice  as  quick  as  the  water,  and  the 
mercury  thirty  times  quicker  than  the  water.  This  phenom- 
enon is  accounted  for  by  the  difference  in  the  amount  of 
latent  heat  that  exists  in  various  substances.  On  the  au- 
thority of  Sir  Humphrey  Davy,  zinc  is  heated  and  cooled 
again  ten  and  three-quarters  times  quicker  than  water,  brass 
ten  and  a  half  times  quicker,  steel  nine  times,  glass  eight 
and  a  half  times,  and  mercury  is  heated  and  cooled  again 
thirty  times  quicker  than  water. 

From  the  above  it  will  be  noticed  that  the  difference  in 
the  time  steel  and  mercury  takes  to  rise  and  fall  to  a  given 
temperature  is  as  nine  to  thirty,  and  also  that  the  difference 
in  the  quantity  of  heat  that  it  takes  to  raise  steel  and  mer- 
cury to  a  given  temperature  is  in  the  ratio  of  nine  to  thirty. 

Now,  without  entering  into  minute  details  on  the  prop- 
erties which  different  substances  possess  for  absorbing  or 
reflecting  heat,  it  is  plain  that  mercury  should  move  in  a 
proportionally  different  atmosphere  from  steel  in  order  to 
be  expanded  or  contracted  a  given  distance  in  the  same 
length  of  time ;  and  to  obtain  this  result  the  amount  of  dif- 
ference in  the  temperature  of  the  atmosphere  at  the  opposite 
ends  of  the  pendulum  must  vary  a  little  more  or  less  accord- 
ing to  the  nature  of  the  material  the  mercury  jars  are  con- 
structed from. 

Differences  in  the  temperature  of  the  atmosphere  of  a 
room  will  generally  vary  according  to  its  size,  the  height 
of  the  ceiling,  and  the  ventilation  of  the  apartment;  and  if 
the  difference  must  continue  to  exist,  it  is  of  importance 
that  the  difference  should  be  uniformly  regular.  We  must 
not  lose  sight  of  the  fact,  however,  that  clocks  having  these 
pendulums,  and  placed  in  apartments  every  way  favorable 
to  an  equal  temperature,  and  in  some  instances,  the  clocks 
and  their  pendulums  incased  in  double  casing  in  order  to 
more  effectually  obtain  this  result,  still  the  rates  of  the 
clock  show  the  same  eccentricities  as  those  placed  in  less 


THE     MODERN     CLOCK.  65 

favorable  position.  This  clearly  shov/s  that  many  changes 
in  the  rates  of  fine  clocks  are  due  to  other  causes  than  a 
change  in  the  temperature  of  the  surounding  atmosphere. 
Still  it  must  be  admitted  that  any  change  in  the  condition  of 
the  atmosphere  that  surrounds  a  pendulum  is  a  most  formid- 
able obstacle  to  be  overcome  by  those  who  seek  to  improve 
compensated  pendulums,  and  it  would  be  of  service  to  them 
to  know  all  that  can  possibly  be  known  on  the  subject. 

The  differences  spoken  of  above  have  resulted  in  some 
practical  improvements,  which  are:  ist,  the  division  of  the 
mercury  into  two,  three  or  four  jars  in  order  to  expose  as 
much  surface  as  possible  to  the  action  of  the  air,  so  that 
the  expansion  of  the  mercury  should  not  lag  behind  that  of 
the  rod,  which  it  will  do  if  too  large  amounts  of  it  are  kept 
in  one  jar.  2nd,  the  use  of  very  thin  steel  jars  made  from 
tubing,  so  that  the  transmission  of  heat  from  the  air  to  the 
mercury  may  be  hastened  as  much  as  possible.  3rd,  the  in- 
crease in  the  number  of  jars  makes  a  thinner  bob  than  a 
single  jar  of  the  same  total  weight  and  hence  gives  an  ad- 
vantage in  decreasing  the  resistant  effect  of  air  friction  in 
dense  air,  thereby  decreasing  somewhat  the  barometric 
error  of  the  pendulum. 

The  original  form  of  mercurial  pendulums,  as  made  by 
Graham,  and  still  used  in  tower  and  other  clocks  where 
extraordinary  accuracy  is  not  required,  was  a  single  jar 
which  formed  the  bob  and  had  the  pendulum  rod  extending 
into  the  mercury  to  assist  in  conducting  heat  to  the  variable 
element  of  the  pendulum.  It  is  shown  in  section  in  Fig, 
ii3,  which  is  taken  from  a  working  drawing  for  a  tower 
clock. 

The  pendulum.  Fig.  13,  is  suspended  from  the  head  or 
cock  shown  in  the  figure,  and  supported  by  the  clock  frame 
itself,  instead  of  being  hung  on  a  wall,  since  the  intention 
is  to  set  the  clock  in  the  center  of  the  clockroom,  and 
also  because  the  weight,  forty  pounds,  is  not  too  much  for 
the  clock  frame  to  carry.    The  head.  A,  forms  a  revolving 


66  THE     MODERN     CLOCK.  ' 

thumb-nut,  which  is  divided  into  sixty  parts  around  the 
circumference  of  its  lower  edge,  and  the  regulating  screw, 
B,  is  threaded  ten  to  the  inch.  A  very  fine  a'djustment  is 
thus  obtained  for  regulating  the  time  of  the  pendulum.  The 
lower  end  of  the  regulating  screw,  B,  holds  the  end  of  the 
pendulum  spring,  E,  which  is  riveted  between  two  pieces 
of  steel,  C,  and  a  pin,  C,  is  put  through  them  and  the  end 
of  the  regulating  screw,  by  which  to  suspend  the  pendulum. 

The  cheeks  or  chops  are  the  pieces  D,  the  lower  edges 
of  which  form  the  theoretical  point  of  suspension  of  the 
pendulum.  These  pieces  must  be  perfectly  square  at  their 
lower  edges,  otherwise  the  center  of  gravity  would  describe 
1  cylindrical  curve.  The  chops  are  clamped  tightly  in  place 
by  the  setscrews,  D',  after  the  pendulum  has  been  hung. 

The  lower  end  of  the  regulating  screw  is  squared  to  fit  the 
ways  and  slotted  on  one  side,  sliding  on  a  pin  to  prevent  its 
turning  and  therefore  twisting  the  suspension  spring  when 
it  is  raised  or  lowered. 

The  spring  is  three  inches  long  between  its  points  of 
suspension,  one  and  three-eighths  inches  wide,  and  one- 
sixtieth  of  an  inch  thick.  Its  lower  end  is  riveted  between 
two  small  blocks  of  steel,  F,  and  suspended  from  a  pin,  F', 
in  the  upper  end  of  the  cap,  G,  of  the  pendulum  rod. 

The  tubular  steel  portion  of  the  pendulum  rod  is  seven- 
eighths  of  an  inch  in  diameter  and  one-thirty-second  of  an 
inch  thickness  of  the  wall.  It  is  enclosed  at  each  end  by  the 
solid  ends,  G  and  L,  and  is  made  as  nearly  air  tight  as 
possible. 

The  compensation  is  by  mercury  inclosed  in  a  cast-iron 
bob.  The  mercury,  the  bob  and  the-  rod  together  weigh 
forty  pounds.  The  bob  of  the  pendulum  is  a  cast-iron  jar, 
K,  three  inches  in  diameter  inside,  one-quarter  inch  thick 
at  the  sides,  and  five-sixteenths  thick  at  the  bottom,  with 
the  cap,  J,  screwed  into  its  upper  end.  The  cap,  J,  forms 
also  the  socket  for  the  lower  end  of  the  pendulum  rod,  H. 
The  rod,  L,  one-quarter  inch  in  diameter,  screws  into  the 
cap,  J,  and  its  large  end  at  the  same  time  forms  a  plug 


THE     MODERN     CLOCK. 


67 


■±; 


Fig.  13. 


68  THE     MODERN     CLOCK. 

for  the  lower  end  of  the  pendulum  tube,  H.  The  pin,  J', 
holds  all  these  parts  together.  The  rod,  L,  extends  nearly  to 
the  bottom  of  the  jar,  and  forms  a  medium  for  the  trans- 
mission of  the  changes  in  temperature  from  the  pendulum 
tube  to  the  mercury.  The  screw  in  the  cap,  J,  is  for  filling 
or  emptying  the  jar.  The  jar  is  finished  as  smoothly  as 
possible,  outside  and  inside,  and  should  be  coated  with  at 
least  three  coats  of  shellac  inside.  Of  course  if  one  was 
building  an  astronomical  clock,  it  would  be  necessary  to 
boil  the  mercury  in  the  jar  in  order  to  drive  off  the  layer  of 
air  between  the  mercury  and  the  walls  of  the  jar,  but  with 
the  smooth  finish  the  shellac  will  give,  in  addition  to  the 
good  work  of  the  machinist,  the  amount  of  air  held  by 
the  jar  can  be  ignored. 

The  cast-iron  jar  was  decided  upon  because  it  was  safer 
to  handle,  can  be  attached  more  firmly  to  the  rod  with  less 
multiplication  of  parts,  and  also  on  account  of  the  weight 
as  compared  with  glass,  which  is  the  only  other  thing  that 
should  be  used,  the  glass  requiring  a  greater  height  of  jar 
for  equal  weight.  In  making  cast  iron  jars,  they  should  al- 
ways be  carefully  turned  inside  and  out  in  order  that  the 
walls  of  the  jar  may  be  of  equal  thickness  throughout;  then 
they  will  not  throw  the  pendulum  out  of  balance  when  they 
are  screwed  up  or  down  on  the  pendulum  rod  in  making 
the  coarse  regulation  before  timing  by  the  upper  screw. 
The  thread  on  the  rod  should  have  the  cover  of  the  jar  at 
about  the  center  of  the  thread  when  nearly  to  time  and 
that  portion  which  extends  into  the  jar  should  be  short 
enough  to  permit  this. 

Ignoring  the  rod  and  its  parts  for  the  present,  and  calling 
the  jar  one-third  of  the  weight  of  the  mercury,  we  shall 
find  that  thirty  pounds  of  mercury,  at  .49  pounds  per  cubic 
inch,  will  fill  a  cylinder  which  is  three  inches  inside  diam- 
eter to  a  height  of  8.816  inches,  after  deducting  for  the 
mass  of  the  rod  L,  when  the  temperature  of  the  mercury  is 
60  degrees  F.     Mercury  expands  one-tenth  in  bulk,  while 


THE     MODERN     CLOCK.  69 

cast-iron  expands  .0066  in  diameter:  so  the  sectional  area 
increases  as  1,0066^  or  1.0132  to  i,  therefore  the  mercury 
will  rise  .1 — .013243,  or  .086757;  then  the  mercury  in  our 
jar  will  rise  .767  of  an  inch  in  the  ordinary  changes  of 
temperature,  making  a  total  height  of  9.58  inches  to  provide 
for;  so  the  jar  was  made  ten  inches  long. 

Pendulums  of  this  pattern  as  used  in  the  high  grade 
English  clocks,  are  substantially  as  follows:  Rod  of  steel 
5-16  inch  diameter;  jar  about  2.1  inches  diameter  inside 
and  8}i  inches  deep  inside.  The  jar  may  be  wrought  or 
cast  iron  and  about  ^  of  an  inch  thick  with  the  cover  to 
screw  on  with  fine  thread,  making  a  tight  joint.  The  cover 
of  the  jar  is  to  act  as  a  nut  to  turn  on  the  rod  for  regula- 
tion. The  thread  cut  on  the  rod  should  be  thirty-six  to 
the  inch,  and  fit  into  the  jar  cover  easily,  so  that  it  may 
turn  without  binding.  With  a  thirty-six  thread  one  turn 
of  the  jar  on  the  rod  changes  the  rate  thirty  seconds  per 
day  and  by  laying  ofT  on  the  edge  of  the  cover  30  divisions, 
a  scale  is  made  by  which  movements  for  one  second  per 
day  are  obtained. 

We  will  now  describe  (Fig.  14)  the  method  of  making  a 
mercurial  pendulum  to  replace  an  imitation  gridiron  pendu- 
lum for  a  Swiss,  pin  escapement  regulator,  such  as  is 
commonly  found  in  the  jewelry  stores  of  the  United  States, 
that  is,  a  clock  in  which  the  pendulum  is  supported  by  the 
plates  of  the  movement  and  swings  between  the  front  plate 
and  the  dial  of  the  movement.  In  thus  changing  our  pendu- 
lum, we  shall  desire  to  retain  the  upper  portion  of  the  old 
rod,  as  the  fittings  are  already  in  place  and  we  shall  save 
considerable  time  and  labor  by  this  course.  As  the  pendu- 
lum is  suspended  from  the  movement,  it  must  be  lig;hter  in 
weight  than  if  it  were  independently  supported  by  a  cast 
iron  bracket,  as  shown  in  Fig.  6,  so  we  will  make  the 
weig^ht  about  that  of  the  one  we  have  removed,  or  about 
twelve  pounds.  If  it  is  desired  to  make  the  pendulum 
heavier,  four  jars  of  the  dimensions  given  would  make  it 


yO  THE     MODERN     CLOCK. 

weigh  about  twenty  pounds,  or  four  jars  of  one  inch  diame- 
ter would  make  a  thinner  bob  and  one  weighing  about 
fourteen  pounds.  As  the  substitution  of  a  different  number 
or  different  sizes  of  jars  merely  involves  changing  the 
lengths  of  the  upper  and  lower  bars  of  the  frame,  further 
drawings  will  be  unnecessary,  the  jeweler  having  sufficient 
mechanical  capacity  to  be  able  to  make  them  for  himself. 

1  might  add,  however,  that  the  late  Edward  Howard,  in 
building  his  astronomical  clocks,  used  four  jars  containing 
twenty-eight  pounds  of  mercury  for  such  movements,  and 
the  perfection  of  his  trains  was  such  that  a  seven-ounce 
driving  weight  was  sufficient  to  propel  the  thirty  pound 
pendulum. 

The  two  jars  are  filled  with  mercury  to  a  height  of  jYz 
inches,  are  i%  inches  in  diameter  outside  and  8%  inches  in 
height  outside.  The  caps  and  foot  pieces  are  screwed  on 
and  when  the  foot  pieces  are  screwed  on  for  the  last  time 
the  screw  threads  should  be  covered  with  a  thick  shellac 
varnish  which,  when  dry,  makes  the  joint  perfectly  air 
tight.  The  jars  are  best  made  of  the  fine,  thin  tubing,  used 
in  bicycles,  which  can  be  purchased  from  any  factory,  of 
various  sizes  and  thickness.  In  the  pendulum  shown  in  the 
illustration,  the  jar  stock  is  close  to  14  wire  gauge,  or  about 

2  mm.  in  thickness.  In  cutting  the  threads  at  the  ends  of  the 
jars  they  should  be  about  36  threads  to  the  inch,  the  same 
number  as  the  threads  on  the  lower  end  of  the  rod  used  to 
carry  the  regulating  nut.  A  fine  thread  makes  the  best  job 
and  the  tightest  joints.  The  caps  to  the  jars  are  turned 
up  from  cold  rolled  shafting,  it  being  generally  good  stock 
and  finishes  well.  The  threads  need  not  be  over  3-16  inch, 
which  is  ample.  Cut  the  square  shoulder  so  the  caps  and 
foot  pieces  come  full  up  and  do  not  show  any  thread  when 
screwed  home.  These  jars  will  hold  ten  pounds  of  mercury 
and  this  weight  is  about  right  for  this  particular  style  of 
pendulum.  The  jars  complete  will  weigh  about  seven  ounces 
each. 


THE     MODERN     CLOCK. 


71 


1 


l.lVtfMut  3 

s  n 


n 


>=i 


/      ,       ,      \ 


\_      '        I 


Fig.  14. 


72  THE     MODERN     CLOCK. 

The  frame  is  also  made  of  steel  and  square  finished 
stock  is  used  as  far  as  possible  and  of  the  quality  used  in  the 
caps.  The  lower  bar  of  the  frame  is  six  inches  long  and 
5/s  inch  square  at  the  center  and  tapered,  as  shown  in  the 
illustration.  It  is  made 'light  by  being  planed  away  on  the 
under  side,  an  end  view  being  shown  at  3.  The  top 
bar  of  the  frame,  shown  at  4,  is  planed  away  also  and 
is  one-half  inch  square  the  whole  length  and  is  six  inches 
long.  The  two  side  rods  are  to  bind  the  two  bars  together, 
and  with  the  four  thumb  nuts  at  the  top  and  bottom  make  a 
strong  light  frame. 

The  pendulum  described  is  nickel  plated  and  polished,  ex,- 
cept  the  jars,  which  are  left  half  dead;  that  is,  they  are 
frosted  with  a  sand  blast  and  scratch  brushed  a  little.  The 
effect  is  good  and  makes  a  good  contrast  to  the  polished 
parts.  The  side  rods  are  five  inches  apart,  which  leaves 
one-half  inch  at  the  ends  outside. 

The  rod  is  5-16  of  an  inch  in  diameter  and  33  inches  long 
from  the  bottom  of  the  frame  at  a  point  where  the  regulat- 
ing nut  rests  against  it  to  the  lower  end  of  the  piece  of  the 
usual  gridiron  pendulum  shown  in  Fig.  14  at  10.  This  piece 
shown  is  the  usual  style  and  size  of  those  in  the  majority 
of  these  clocks  and  is  the  standard  adopted  by  the  makers. 
This  piece  is  11%  inches  long  from  the  upper  leaf  of  the 
suspension  spring,  which  is  shown  at  12,  to  the  lower  end 
marked  10.  By  cutting  out  the  lower  end  of  this  piece,  as 
showr  at  10,  and  squaring  the  upper  end  of  the  rod,  pin- 
ning it  into  the  piece  as  shown,  the  union  can  be  made  easily 
and  any  little  adjustments  for  length  can  be  made  by  drilling 
another  set  of  holes  in  the  rod  and  raising  the  pendulum  by 
so  doing  to  the  correct  point.  A  rod  whose  total  length 
is  37  inches  will  leave  2  inches  for  the  prolongation  below 
the  frame  carrying  the  regulating  nut,  9,  and  for  the  portion 


THE     MODERN     CLOCK.  73 

squared  at  the  top,  and  will  then  be  so  long  that  the  rate 
of  the  clock  will  be  slow  and  leave  a  surplus  to  be  cut  off 
either  at  the  top  or  bottom,  as  may  seem  best. 

The  screw  at  the  lower  end  carrying  the  nut  should  have 
36  threads  to  the  inch  and  the  nut  graduated  to  30  divisions, 
each  of  which  is  equal  in  turning  the  nut  to  one  minute  in 
24  hours,  fast  or  slow,  as  the  case  may  be. 

The  rod  should  pass  through  the  frame  bars  snugly  and 
not  rattle  or  bind.  It  also  should  have  a  slot  cut  so  that  a  pin 
can  be  put  through  the  upper  bar  of  the  frame  to  keep  the 
frame  from  turning  on  the  rod  and  yet  allow  it  to  move  up 
and  down  about  an  inch.  The  thread  at  the  lower  end  of  the 
rod  should  be  cut  about  two  inches  in  length  and  when  cut- 
ting off  the  rod  for  a  final  length,  put  the  nut  in  the  middle 
of  the  run  of  the  thread  and  shorten  the  rod  at  the  top. 
This  will  be  found  the  most  satisfactory  method,  for  when 
all  is  adjusted  the  nut  will  stand  in  the  middle  of  its  scope 
and  have  an  ^qual  run  for  fast  or  slow  adjustment.  With 
the  rod  of  the  full  length  as  given,  this  pendulum  had  to  be 
cut  at  the  top  about  one  inch  to  bring  to  a  minute  or  two  in 
twenty-four  hours,  and  this  left  all  other  points  below  cor- 
rected. The  pin  in  the  rod  should  be  adjusted  the  last  thing, 
as  this  allows  the  rod  to  slide  on  the  pin  equal  distances  each 
way.  One  inch  in  the  raising  or  lowering  of  the  frame  on 
the  rod  will  alter  the  rate  for  twenty- four  hours  about 
eighteen  minutes. 

Many  attempts  have  been  made  to  combine  the  good  qual- 
ities of  the  various  forms  of  pendulums  and  thus  produce  an 
instrument  which  would  do  better  work  under  the  severe 
exactions  of  astronomical  observatories  and  master  clocks 
controlling  large  systems.  The  reader  should  understand 
that,  just  as  in  watch  work,  the  difficulties  increase  enor- 
mously the  nearer  we  get  towards  absolute  accuracy,  and 


74  THE    MODERN    CLOCK. 

while  anybody  can  make  a  pendulum  which  will  stay  within 
a  minute  a  month,  it  takes  a  very  good  one  to  stay  within 
five  seconds  per  month,  under  the  conditions  usually  found 
in  a  store,  and  such  a  performance  makes  it  totally  unfit  for 
astronomical  work,  where  variations  of  not  over  five-* 
thousandths  of  a  second  per  day  are  demanded.  In  order 
to  secure  such  accuracy  every  possible  aid  is  given  to  the 
pendulum.  Barometric  errors  are  avoided  by  enclosing  it  in 
an  airtight  case,  provided  with  an  airpump ;  the  temperature 
is  carefully  maintained  as  nearly  constant  as  possible  and  its 
performance  is  carefully  checked  against  the  revolutions  of 
the  fixed  stars,  while  various  astronomers  check  their  ob- 
servations against  each  other  by  correspondence,  so  that 
each  can  get  the  rate  of  his  clock  by  calculations  of  obser- 
vations and  the  law  of  averages,  eliminating  personal  errors. 

One  of  the  successful  attempts  at  such  a  combination  of 
mercury  and  metallic  pendulums  is  that  of  Riefler,  as  shown 
in  Fig.  15,  which  illustrates  a  seconds  pendulum  one-thir- 
tieth of  the  actual  size. 

It  consists  of  a  Mannesmann  steel  tube  (rod),  bore  16 
mm.,  thickness  of  metal  i  mm.,  filled  with  mercury  to 
about  two-thirds  of  its  length,  the  expansion  of  the  mercury 
in  the  tube  changing  the  center  of  weight  an  amount  suffi- 
cient to  compensate  for  the  lengthening  of  the  tube  by 
heat,  or  vice  versa.  The  pendulum,  has  further, 
a  metal  bob  weighing  several  kilograms,  and  shaped  to 
cut  the  air.  Below  the  bob  are  disc  shaped  weights,  attached 
by  screw  threads,  for  correcting  the  compensation,  the 
number  of  which  may  be  increased  or  diminished  as  ap- 
pears necessary. 

Whereas  in  the  Graham  pendulum  regulation  for  tem- 
perature is  effected  by  altering  the  height  of  the  column  of 


THE     MODERN     CLOCK 


75 


mercury,  in  this  pendulum  it  is  effected  by 
changing  the  position  of  the  center  of 
weight  of  the  pendulum  by  moving  the 
regulating  weights  referred  to,  and  thus 
the  height  of  the  column  of  mercury  always 
remains  the  same,  except  as  it  is  influenced 
by  the  temperature. 

A  correction  of  the  compensation  should 
be  effected,  however,  only  in  case  the  pen- 
dulum is  to  show  sidereal  time,  instead  of 
mean  solar  time,  for  which  latter  it  is  cal- 
culated. In  this  case  a  weight  of  no  to 
120  grams  should  be  screwed  on  to  correct 
the  compensation. 

In  order  to  calculate  the  effect  of  the 
compensation,  it  is  necessary  to  know  pre- 
cisely the  co-efficients  of  the  expansion  by 
heat  of  the  steel  rod,  the  mercury,  and  the 
material  of  which  the  bob  is  made. 

The  last  two  of  these  co-efficients  of  ex- 
pansion are  of  subordinate  importance,  the 
two  adjusting  screws  for  shifting  the  bob 
up  and  down  being  fixed  in  the  middle  of 
the  latter.    A  slight  deviation  is,  therefore, 
of  no  consequence.     In  the  calculation  for 
all  these  pendulums  the  co-efficient  for  the 
bob  is,  therefore,  fixed  at  0.000018,  and  for 
the  mercury  at  0.00018136,  being  the  clos- 
est approximation  hitherto  found  for  chem- 
ically pure  mercury,  such  as  that  used  in 
these  pendulums. 
The  co-efficient  of  the  expansion  of  the  steel  rod  is,  how- 
ever, of  greater  importance.    It  is  therefore,  ascertained  for 
every  pendulum  constructed  in  Mr.  Riefler's  factory,  by  the 
physikalisch-technische    Reichsanstalt    at    Charlottenburg, 
examinations  showing,  in  the  case  of  a  large  number  of  sim- 


Fig.  15. 


76  THE     MODERN     CLOCK. 

ilar  steel  rods,  that  the  co-efficient  of  expansion  lies  be- 
tween 0.00001034  and  0.00001162. 

The  precision  with  which  the  measurements  are  carried 
out  is  so  great  that  the  error  in  compensation  resulting 
from  a  possible  deviation  from  the  true  value  of  the  co- 
efficient of  expansion,  as  ascertained  by  the  Reichsanstalt, 
does  not  amount  to  over  ±  0.0017;  and,  as  the  precision 
with  which  the  compensation  for  each  pendulum  may  be 
calculated  absolutely  precludes  any  error  of  consequence, 
Mr.  Riefler  is  in  a  position  to  guarantee  that  the  probable 
error  of  compensation  in  these  pendulums  will  not  exceed 
±  0.005  seconds  per  diem  and  ±  j°  variation  in  tem- 
perature. 

A  subsequent  correction  of  the  compensation  is,  there- 
fore, superfluous,  whereas,  with  all  other  pendulums  it  is 
necessary,  partly  because  the  co-efficients  of  expansion  of 
the  materials  used  are  arbitrarily  assumed ;  and  partly 
because  none  of  the  formulae  hitherto  employed  for  calcu- 
lating the  compensation  can  yield  an  exact  result,  for  the 
reason  that  they  neglect  to  notice  certain  important  influ- 
ences, in  particular  that  of  the  weight  of  the  several  parts 
of  the  pendulum.  Such  formulae  are  based  on  the  assump- 
tion that  this  problem  can  be  solved  by  simple  geometrical 
calculation,  whereas,  its  exact  solution  can  be  arrived  at 
only  with  the  aid  of  physics. 

This  is  hardly  the  proper  place  for  details  concerning 
the  lengthy  and  rather  complicated  calculations  required 
by  the  method  employed.  It  is  intended  to  publish  them 
later,  either  in  some  mathematical  journal  or  in  a  separate 
pamphlet.  Here  I  will  only  say  that  the  object  of  the 
whole  calculation  is  to  find  the  allowable  or  requisite  weight 
of  the  bob,  i.  e.,  the  weight  proportionate  to  the  co-efficients 
of  expansion  of  the  steel  rod,  dimensions  and  weight  of  the 
rod  and  the  column  of  mercury  being  given  in  each  sep- 
arate case.    To  this  end  the  relations  of  all  the  parts  of  the 


THE     MODERN     CLOCK.  77 

pendulum,  both  in  regard  to  statics  and  inertia,  have  to  be 
ascertained,  and  for  various  temperatures. 

A  considerable  number  of  these  pendulums  have  already 
been  constructed,  and  are  now  running  in  astronomical  ob- 
servatories. One  of  them  is  in  the  observatory  of  the  Uni- 
versity of  Chicago,  and  others  are  in  Europe.  The  precision 
of  this  compensation  which  was  discovered  by  purely  theo- 
retical computations,  has  been  thoroughly  established  by  the 
ascertained  records  of  their  running  at  different  temper- 
atures. 

The  adjustment  of  the  pendulums,  which  is,  of  course, 
almost  wholly  without  influence  on  the  compensation,  can 
be  effected  in  three  different  ways: 

(i.)  The  rough  adjustment,  by  screwing  the  bob  up  or 
down. 

(2.)  A  finer  adjustment,  by  screwing  the  correction 
discs  up  or  down. 

(3.)  The  finest  adjustment,  by  putting  on  additional 
weights. 

These  weights  are  to  be  placed  on  a  cup  attached  to  a 
special  part  of  the  rod  of  the  pendulum.  Their  shape  and 
size  is  such  that  they  can  be  readily  put  on  or  taken  off 
while  the  pendulum  is  swinging.  Their  weight  bears  a 
fixed  proportion  to  the  static  momentum  of  the  pendulum, 
so  that  each  additional  weight  imparts  to  the  pendulum,  for 
iwenty-four  hours,  an  acceleration  expressed  in  even  sec- 
onds and  parts  of  seconds,  and  marked  on  each  weight. 

Each  pendulum  is  accompanied  with  additional  weights 
of  German  silver,  for  a  daily  acceleration  of  i  second  each, 
and  ditto  of  aluminum  for  an  acceleration  of  0.5  and  0.1 
second  respectively. 

A  metal  clasp  attached  on  the  rear  side  of  the  clock-case, 
may  be  pushed  up  to  hold  the  pendulum  in  such  a  way  that 
it  can  receive  no  twisting  motion  during  adjustment. 

Further,  a  pointer  is  attached  to  the  lower  end  of  the 
pendulum,  for  reading  off  the  arc  of  oscillation. 


78  THE     MODERN     CLOCK. 

The  essential  advantages  of  this  pendulum  over  the  mer- 
curial compensation  pendulums  are  the  following : 

(i.)  It  follows  the  changes  of  temperature  more  rap- 
idly, because  a  small  amount  of  mercury  is  divided  over  a 
greater  length  of  pendulum,  whereas,  in  the  older  ones  the 
entire  (and  decidedly  larger)  mass  of  mercury  is  situ- 
ated in  a  vessel  at  the  lower  end  of  the  pendulum  rod. 

(2.)  For  this  reason  differences  in  the  temperature  of 
the  air  at  different  levels  have  no  such  disturbing  influence 
on  this  pendulum  as  on  the  others. 

(3.)  This  pendulum  is  not  so  strongly  influenced  as 
the  others  by  changes  in  the  atmospheric  pressure,  because 
the  principal  mass  of  the  pendulum  has  the  shape  of  a  lens, 
and  therefore  cuts  the  air  easily. 


CHAPTER   V. 

REGULATIONS,    SUSPENSIONS,    CRUTCHES  AND   MINOR   POINTS. 

Regulation. — The  reader  will  have  noticed  that  in  de- 
scribing the  various  forms  of  seconds  pendulums  we  have 
specified  either  eighteen  or  thirty-six  threads  to  the  inch; 
this  is  because  a  revolution  of  the  nut  with  such  a  thread 
gives  us  a  definite  proportion  of  the  length  of  the  rod,  so 
that' it  means  an  even  number  of  seconds  in  twenty-four 
hours. 

Moving  the  bob  up  or  down  1-18  inch  makes  the  clock 
having  a  seconds  pendulum  gain  or  lose  in  twenty-four 
hours  one  minute,  hence  the  selecting  definite  numbers  of 
threads  has  for  its  reason  a  philosophical  standpoint,  and  is 
not  a  matter  of  convenience  and  chance,  as  seems  to  be  the 
practice  with  many  clockmakers.  With  a  screw  of  eighteen 
threads,  we  shall  get  one  minute  change  of  the  clock's 
rate  in  twenty-four  hours  for  every  turn  of  the  nut,  and 
if  the  nut  is  divided  into  sixty  parts  at  its  edge,  each  of 
these  divisions  will  make  a  change  of  the  clock's  rate  of  one 
second  in  twenty-four  hours.  Thus  by  using  a  thread 
having  a  definite  relation  to*  the  length  of  the  rod  regu- 
lating is  made  comparatively  easy,  and  a  clock  can  be 
brought  to  time  without  delay.  Suppose,  after  comparing 
your  clock  for  three  or  four  days  with  some  standard, 
you  find  it  gains  twelve  seconds  per  day,  then,  turning  the 
nut  down  twelve  divisions  will  bring  the  rate  down  to 
within  one  second  a  day  in  one  operation,  if  the  screw  is 
eighteen  threads.  With  the  screw  thirty-six  threads  the 
nut  will  require  moving  just  the  same  number  of  divisions, 
only  the  divisions  are  twice  as  long  as  those  with  the  screw 
of  eighteen  threads. 

79 


8o  THE     MODERN     CLOCK. 

The  next  thing  is  the  size  and  weight  of  the  nut.  If  it  is 
to  be  placed  in  the  middle  of  the  bob  as  in  Figs.  lo,  12  and 
15,  it  should  project  slightly  beyond  the  surface  and  its 
diameter  will  be  governed  by  the  thickness  of  the  bob.  If 
Jt  is  an  internal  nut,  worked  by  means  of  a  sleeve  and  disc, 
as  in  Fig.  9,  the  disc .  should  be  of  sufficient  diameter  to 
make  the  divisions  long  enough  to  be  easily  read.  If  the 
nut  is  of  the  class  shown  in  Fig.  5,  6,  7,  a  nut  is  most  con- 
venient, I  inch  in  diameter,  and  cut  on  its  edge  into  thirty 
equal  divisions,  each  of  which  is  equal  to  one  second  in 
change  of  rate  in  twenty-four  hours,  if  the  screw  has  thirty- 
six  threads  to  the  inch.  This  gives  3.1416  inches  of  cir- 
cumference for  the  thirty  divisions,  which  makes  them  long 
enough  to  be  subdivided  if  we  choose,  each  division  being  a 
little  over  one-tenth  of  an  inch  in  length,  so  that  quarter- 
seconds  may  be  measured  or  estimated. 

With  some  pendulums,  Fig.  13,  the  bob  rotates  on  the 
rod,  and  is  in  the  form  of  a  cylinder,  say  8^  inches  long 
by  25^  inches  in  diameter,  and  the  bob  then  acts  on  its  rod 
as  the  nut  does,  and  moves  up  and  down  when  turned,  and 
in  this  form  of  bob  the  divisions  are  cut  on  the  outside  edge 
of  the  cover  of  the  bob,  and  are  so  long  that  each  one  is  sub- 
divided into  five  or  ten  smaller  divisions,  each  altering  the 
clock  .2  or  .1  second  per  day. 

On  the  top  of  the  bob  turn  two  deep  lines,  close  to  the 
edge,  about  5^ -inch  apart,  and  divide  the  whole  diameter 
into  thirty  equal  divisions,  and  subdivide  each  of  the  thirty 
into  five,  and  this  will  give  seconds  and  fifths  of  seconds 
for  twenty-four  hours.  Each  even  seconds  division  should 
be  marked  heavier  than  the  fraction,  and  should  be  marked 
from  one  to  thirty  with  figures.  Just  above  the  cover  on 
the  rod  should  slide  a  short  tube,  friction  tight,  and  to  this 
a  light  index  or  hand  should  be  fastened,  the  point  of  which 
just  reaches  the  seconds  circle  on  the  bob  cover,  and  thus 
indicates  the  division,  its  number  and  fraction.  The  tube 
slides  on  the  rod  because  the  exact  place  of  the  hand  can- 


THE     MODERN     CLOCK.  8l 

not  be  settled  until  it  has  been  settled  by  experiment.  After 
this  it  can  be  fastened  permanently,  if  thought  best,  though 
as  described  it  will  be  all  sufficient.  While  the  bob  is  being 
raised  or  lowered  to  bring  the  clock  to  its  rate,  the  bob 
might  get  too  far  away  or  too  near  to  the  index  and  neces- 
sitate its  being  shifted,  and  if  friction  tight  this  can  be  read- 
ily accomplished,  and  the  hand  be  brought  to  just  coincide 
with  the  divisions  and  look  well  and  be  a  means  of  accom- 
plishing very  accurate  minute  adjustments. 

Suspensions. — Suspensions  are  of  four  kinds,  cord,  wire 
loop,  knife  edges  and  springs.  Cords  are  generally  of 
loosely  twisted  silk  and  are  seldom  found  except  in  the 
older  clocks  of  French  or  Swiss  construction.  They  have 
been  entirely  displaced  in  the  later  makes  of  European 
manufactures  by  a  double  wire  loop,  in  which  the  pendu- 
lum swings  from  a  central  eye  in  the  loop,  while  the  loop 
rocks  upon  a  round  stud  by  means  of  an  eye  at  each  end 
of  the  loop.  The  eyes  should  all  be  in  planes  parallel  to  the 
plane  of  oscillation  of  the  pendulum,  otherwise  the  bob  will 
take  an  elliptical  path  instead  of  oscillating  in  a  plane.  They 
should  also  be  large  enough  to  roll  without  friction  upon 
the  stud  and  center  of  the  loop,  as  any  slipping  or  sliding 
of  either  will  cause  them  to  soon  wear  out,  besides  affecting 
the  rate  of  the  pendulum.  Properly  constructed  loops  will 
give  practically  no  friction  and  make  a  very  free  suspension 
that  will  last  as  long  as  the  clock  is  capable  of  keeping 
time,  although  it  seems  to  be  a  very  weak  and  flimsy 
method  of  construction  at  first  sight.  Care  should  be  taken 
in  such  cases  to  keep  the  bob  from  turning  when  regulating 
the  clock,  or  the  effect. upon  the  pendulum  will  be  the  same 
as  if  the  eyes  were  not  parallel. 

Knife-edge  suspensions  are  also  rare  now,  having  been 
displaced  by  the  spring,  as  it  was  found  the  vibrations  were 
too  free  and  any  change  in  power  introduced  a  circular  error 
(See  Fig.  4)   by  making  the  long  swings  in  longer  time. 


82  THE     MODERN     CLOCK. 

They  are  still  to  be  found,  however,  and  in  repairing  clocks 
containing  them  the  following  points  should  be  observed : 
The  upper  surface  of  the  stud  on  which  the  pendulum 
swings  should  carry  the  knife  edge  at  its  highest  point, 
exactly  central  with  the  line  of  centers  of  the  stud,  so  that 
when  the  pendulum  hangs  at  rest  the  stud  shall  taper  equally 
on  both  sides  of  the  center,  thus  giving  equal  freedom  to 
both  sides  of  the  swing.  Care  should  be  taken  that  the  stud 
is  firmly  fixed,  with  the  knife  edge  exactly  at  right  angles 
to  the  movement,  and  also  to  the  back  of  the  case.  The  sus- 
pension stud  and  the  block  on  the  rod  should  be  long  enough 
to  hold  the  pendulum  firmly  in  line,  as  the  angle  in  the  top 
of  the  rod  must  be  the  sole  means  of  keeping  the  pendu- 
lum swinging  in  plane.  The  student  will  also  perceive  the 
necessity  of  making  the  angle  occupy  the  proper  position 
on  the  rod,  especially  if  the  latter  be  flat.  In  repairing 
this  suspension  it  is  usual  to  make  the  plate,  fasten  it  in 
place  and  then  drill  and  file  out  the  hole,  as  it  is  easier  to 
get  the  angles  exactly  in  this  way  than  to  complete  the 
plate  and  then  attempt  to  fasten  it  in  the  exact  position  in 
which  it  should  be.  After  fastening  the  plates  in  position 
on  the  rod,  two  holes  should  be  drilled,  a  small  one  at  the 
apex  of  the  angle  (which  must  be  exactly  square  and  true 
with  the  rod),  and  a  larger  one  below  it  large  enough  to 
pass  the  files  easily.  The  larger  hole  can  then  be  enlarged 
to  the  proper  size,  filing  the  angle  at  the  top  in  such  a  way 
that  the  small  hole  first  drilled  forms  the  groove  at  the 
apex  of  the  angle  in  which  the  knife  edge  of  the  stud  shall 
v/ork  when  it  is  completed.  Knife-edge  suspensions  are 
unfitted  for  heavy  pendulums,  as  the  weight  causes  the 
knife  edge  to  work  into  the  groove  and  cut  it,  even  if  the 
latter  oe  jeweled.  Both  the  edge  and  groove  should  bt 
hardened  and  polished. 

Pendulum   Suspension   Springs. — Next  in  importance 
to   the   pendulum   is    its   suspension   spring.     This   spring 


THE     MODERN     CLOCK.  83 

should  be  just  stiff  enough  to  make  the  pendulum  swing  in 
all  its  vibrations  in  the  sam.e  time ;  that  is,  if  the  pendulum 
at  one  time  swung  at  the  bottom  of  the  jar  i^  inch  each 
side  of  the  center,  and  at  another  time  it  swung  only  i  inch 
each  side,  that  the  two  should  be  made  in  exactly  one 
second.  The  suspension  springs  are  a  point  in  the  con- 
struction of  a  fine  pendulum,  that  there  has  been  very 
much  theorizing  on,  but  the  experiments  have  never  thus  far 
exactly  corroborated  the  theories  and  there  are  no  definite 
rules  to  go  by,  but  every  maker  holds  to  that  plan  and  con- 
struction that  gives  his  particular  works  the  best  results.  A 
spring  of  sufficient  strength  to  materially  influence  the 
swing  of  the  pendulum  is  of  course  bad,  as  it  necessitates 
more  power  to  give  the  pendulum  its  proper  motion  and 
hence  there  is  unnecessary  wear  on  the  pallets  and  escape 
wheel  teeth,  and  too  weak  a  spring  is  also  bad,  as  it  would 
not  correct  any  inequalities  in  the  time  of  swing  and  would 
in  time  break  from  overloading,  as  its  granular  structure 
would  finally  change,  and  rupture  of  the  spring  would  fol- 
low. The  office  of  a  spring  is  to  sustain  the  weight  without 
detriment  to  strength  and  elasticity,  and  if  so  proportioned 
to  the  weight  as  to  be  just  right,  it  will  make  the  long  and 
short  swings  of  the  pendulum  of  equal  duration.  When  a 
pendulum  hung  by  a  cord  or  knife  edge  insttad  of  a  spring 
is  regulated  to  mean  time  and  swings  just  two  inches  at  the 
bottom,  any  change  in  the  power  that  swings  the  pendu- 
lum will  increase  its  movement  or  decrease  it,  and  in  either 
case  the  rate  will  change,  but  with  a  proper  spring  the  rate 
will  be  constant  under  like  conditions.  The  action  of  the 
spring  is  this:  In  the  long  swings  the  spring,  as  it  bends, 
lifts  the  pendulum  bob  up  a  little  more  than  the  arc  of  the 
normal  circle  in  which  it  swings,  and  consequently  when 
the  bob  descends,  in  going  to  the  center  of  its  swing,  it  falls 
a  little  quicker  than  it  does  when  held  by  a  cord,  and  this 
extra  quick  drop  can  be  made  to  neutralize  the  extra  time 
taken  by  the  bob  in  making  extra  long  swings.     See  Fig.  4. 


84 


THE     MODERN     CLOCK. 


This  action  is  the  isochronal  action  of  the  spring,  the  same 
that  is  attained  in  isochronal  hair  springs  in  watches. 

As  with  the  hairspring,  it  is  quite  necessary  that  the  pen- 
dulum spring  be  accurately  adjusted  to  isochronism  and  my 
advice  to  every  jeweler  is  to  thoroughly  test  his  regulator, 
which  can  easily  be  done  by  changing  the  weight  or  motive 
power.  If  the  test  should  prove  the  lack  of  isochronism  he 
can  adjust  it  by  following  these  simple  rules.  Fig.  i6  is  the 
pendulum  spring  or  leaf.  If  the  short  arcs  should  prove  the 
slowest,  make  the  spring  a  trifle  thinner  at  B ;  if  fastest,  re- 
duce the  thickness  of  the  spring  at  A.  Continue  the  test 
until  the  long  and  short  arcs  are  equal.  In  doing  this  care 
must  be  taken  to  thin  each  spring  equally,  if  it  is  a  double 
spring,  and  each  edge  equally,  if  a  single  spring,  as  if  one 
side  be  left  thicker  than  the  other  the  pendulum  will  wabble. 

The  cause  of  a  pendulum  wabbling  is  that  there  must  be 
something  wrong  with  the  suspension  spring,  or  the  bridge 


B-A 


a 


Err 


□  E 


Fig,  16. 


that  holds  the  spring.  If  the  suspension  spring  is  bent  or 
kinked,  the  pendulum  will  wabble ;  or  if  the  spring  should 
be  of  an  unequal  thickness  it  will  have  the  same  effect  on 
the  pendulum;  but  the  main  cause  of  the  pendulum  wab- 
bling in  American  clocks  is  that  the  slot  in  the  bridge  that 
holds  the  spring,  or  the  slot  in  the  slide  that  works  up  and 
down  on  the  spring  (which  is  used  to  regulate  the  clock)  is 
not  parallel.  When  this  slot  is  not  parallel  it  pinches  the 
spring,  front  or  back,  and  allows  it  to  vibrate  more  where 
it  is  the  freest,  causing  the  pendulum  to  wabble.    We  have 


THE    MODERN    CLOCK.  85 

found  that  by  making  these  slots  parallel  the  wabbling  of  the 
pendulum  has  ceased  in  most  all  cases.  If  the  pallet  staff 
is  not  at  right  angles  to  the  crutch,  wabbling  may  be  caused 
by  the  oblique  action  of  the  crutch.  This  often  happens 
when  the  movement  is  not  set  square  in  the  case. 

It  occasionally  happens  in  mantel  clocks  that  the  pendu- 
lum when  brought  to  time  is  just  too  long  for  the  case  when 
too  thick  a  spring  is  used.  In  such  a  case  thinning  the 
spring  will  require  the  bob  to  be  raised  a  little  and  also 
give  a  better  motion.  If  compelled  to  make  a  spring  use 
a  piece  of  mainspring  about  .007  thick  and  ^  wide  for 
small  pendulums  and  the  same  spring  doubled  for  heavier 
pendulums,  making  the  acting  part  of  the  spring  about  1.5 
inches  long. 

The  suspension  spring  for  a  rather  heavy  pendulum  is 
better  divided,  that  is,  two  springs,  held  by  two  sets  of 
clamps,  and  jointly  acting  as  one  spring.  The  length  will 
be  the  same  as  to  the  acting  part,  and  that  part  held  at  each 
end  by  the  clamps  may  be  ^  inch  long;  total  length,  1.5 
inches  with  ^  inch  at  each  end  held  in  the  clamps.  These 
clamps  are  best  soldered  on  to  the  spring  with  very  low 
flowing  solder  so  as  not  to  draw  the  temper  of  the  spring, 
and  then  two  rivets  put  through  the  whole,  near  the  lower 
edge  of  the  clamps.  The  object  of  securing  the  clamps 
so  firmly  is  so  that  the  spring  may  not  bend  beyond  the 
edge  of  the  clamps,  as  if  this  should  take  place  the  clock  will 
be  thrown  off  of  its  rate.  After  a  time  the  rate  would 
settle  and  become  steady,  but  it  only  causes  an  extra  period 
of  regulating  that  does  not  occur  when  the  clamps  hold 
the  spring  immovable  at  this  point.  About  in  the  center  of 
each  of  the  clamps,  when  soldered  and  riveted,  is  to  be  a 
hole  bored  for  a  pin,  which  pins  the  clamp  into  the  bracket 
and  holds  the  weight  of  the  pendulum. 

The  width  of  this  compound  spring  for  a  seconds'  pendu- 
lum of  average  weight  may  be  .60  inch,  from  outside  to 
outside,  each  spring  .15  inch  wide.     This  will  separate  the 


86 


THE    MODERN    CLOCK. 


Springs  .30  inch  in  the  center.  With  this  form  of  spring, 
the  lower  end  of  each  spring  being  held  in  a  pair  of  clamps, 
the  clamps  will  have  to  be  let  into  the  top  of  the  roa,  and 
held  in  by  a  stout  pin,  or  the  pendulum  finished  with  a  hook 
which  will  fit  the  clamp.  In  letting  the  clamp  into  the 
rod,  the  clamp  should  just  go  into  the  mortise  and  be  with- 
out side  shake,  but  tilt  each  way  from  the  center  a  little 
on  the  pin,  so  that  when  the  pendulum  is  hung  it  may  hang 
perpendicular,  directly  in  the  center  of  both  springs.  Also, 
the  top  pair  of  clamps  should  fit  into  a  bracket  without 
shake,  and  tilt  a  little  on  a  pin,  the  same  as  the  lower  clamps. 
These  two  points,  each  moving  a  little,  helps  to  take  any 
side  twist  away,  and  allows  the  whole  mechanism  to  swing 
in  line  with  the  center  of  gravity  of  the  mass  from  end  to 
end.  With  the  parts  well  made,  as  described,  the  bob  will 
swing  in  a  straight  line  from  side  to  side,  and  its  path  will 
be  without  any  other  motion  except  the  one  of  slight  curva- 
ture, due  to  being  suspended  by  a  fixed  point  at  the  upper 
clamp. 

Pendulum  Supports. — Stability  in  the  movement  and  in 
the  suspension  of  the  pendulum  is  very  necessary  in  all 
forms  of  clocks  for  accurate  time-keeping.  The  pendulum 
should  be  hung  on  a  bracket  attached  to  the  back  of  the 
case  (see  Fig.  6),  and  not  be  subject  to  disturbance  when 
the  movement  is  cleaned.  Also  the  movement  should  rest 
on  two  brackets  attached  to  the  bracket  holding  the  pendu- 
lum and  the  whole  be  very  firmly  secured  to  the  back  board 
of  the  case.  Screws  should  go  through  the  foot-pieces  of 
the  brackets  and  into  a  stone  or  brick  wall  and  be  very 
firmly  held  against  the  wall  just  back  of  the  brackets.  Any 
instability  in  this  part  of  a  clock  is  very  productive  of  poor 
rates.  The  bracket,  to  be  in  its  best  form,  is  made  of  cast 
iron,  with  a  large  foot  carrying  all  three  separate  brackets, 
well  screwed  to  a  strong  back-board  and  the  whole  secured 
to  the  masonry  by  bolts.     Too  much  firmness  cannot  be 


THE    MODERN    CLOCK.  87 

attained,  as  a  lack  of  it  is  a.  very  great  fault,  and  many  a 
good  clock  is  a  very  poor  time-keeper,  due  to  a  lack  of  firm- 
ness in  its  supports  and  fastenings.  The  late  Edward  How- 
ard used  to  make  his  astronomical  clocks  with  a  heavy  cast 
iron  back,  to  which  the  rest  of  the  case  was  screwed,  so 
that  the  pendulum  should  not  swing  the  case.  Any  external 
influence  that  vibrates  a  wall  or  foundation  on  which  a  clock 
is  placed,  is  a  disturbing  influence,  but  an  instability  in  a 
clock's  attachment  to  such  supports  is  a  greater  one.  Many 
pendulums  swing  the  case  in  which  they  hang  (from  un- 
stable setting  up)  and  never  get  down  to  or  maintain  a 
satisfactory  rate  from  that  cause.  This  is  also  aggra- 
vated by  the  habit  of  placing  grandfather  clocks  on  stair 
landings  or  other  places  subject  to  jarring.  The  writer 
knows  of  several  clocks  which,  after  being  cleaned,  kept 
stopping  until  raised  off  the  floor  and  bolted  to  the  wall, 
when  they  at  once  took  an  excellent  rate.  The  appearance 
of  resting  on  the  floor  may  be  preserved,  if  desirable,  by 
raising  the'  clock  only  half  an  inch  or  so,  just  enough  to 
free  it  from  the  floor. 

Crutches. — The  impulse  is  transmitted  to  the  pendulum 
from  the  pallet  staff  by  means  of  a  wire,  or  slender  rod, 
fastened  at  its  upper  end  to  the  pallet  staff  and  having  its 
lower  end  terminating  in  a  fork  (crutch),  loop,  or  bent 
at  right  angles  so  as  to  work  freely  in  a  slot  in  the  rod. 
It  is  also  called  the  verge  w^re,  owing  to  the  fact  that  older 
writers  and  many  of  the  older  workmen  called  the  pallet 
fork  the  verge,  thus  continuing  the  older  nomenclature, 
although  of  necessity  the  verge  disappeared  when  the  crown 
wheel  was  discarded. 

In  order  to  avoid  friction  at  this  very  important  point, 
the  centers  of  both  axes  of  oscillation,  that  of  the  pallet 
arbor  and  fet  of  the  pendulum  spring,  where  it  bends, 
should  be  in  a  straight  horizontal  line.  If,  for  instance,  the 
center  of  suspension  of  the  pendulum  be  higher,  then  the 


88  THE    MODERN    CLOCK. 

fork  and  the  pendulum  describe  two  different  arcs  of  circles ; 
that  of  the  pendulum  will  be  greater  than  that  of  the  fork 
at  their  meeting  point.  If,  however,  the  center  of  suspen- 
sion of  the  pendulum  be  lower  than  that  of  the  fork,  they 
will  also  describe  two  different  arcs,  and  that  of  the  pendu- 
lum will  be  smaller  than  that  of  the  fork  at  their  point  of 
meeting.  This,  as  can  be  readily  understood,  will  cause 
friction  in  the  fork,  the  pendulum  going  up  and  down  in  it. 
This  is  prevented  when,  as  stated  before,  the  center  of  sus- 
pension of  the  pendulum  is  in  the  prolonged  straight  imagin- 
ary line  going  through  the  center  of  the  pivots  of  the  fork, 
which  will  cause  the  arcs  described  by  the  fork  and  the  pen- 
dulum to  be  the  same.  It  will  be  well  understood  from  the 
foregoing  that  the  pendulum  should  neither  be  suspended 
higher  nor  lower,  nor  to  the  left,  nor  to  the  right  of  the 
fork. 

If  the  centers  of  motion  do  not  coincide,  as  is  often  the 
case  with  cheap  clocks  with  recoil  escapements,  any  rough- 
ness of  the  pendulum  rod  where  it  slides  on  the  crutch 
will  stop  the  clock,  and  repairers  should  always  see  to  it 
that  this  point  is  made  as  smooth  as  possible  and  be  very 
slightly  oiled  when  setting  up.  If  putting  in  a  new  verge 
wire,  the  workman  can  always  tell  where  to  bend  it  to  form 
the  loop  by  noticing  where  the  rod  is  worn  and  forming  the 
loop  so  that  it  will  reach  the  center  of  that  old  crutch  or 
loop  mark  on  the  pendulum  rod.  If  the  verge  wire  is  too 
long,  it  will  give  too  great  an  arc  to  the  pendulum  if  the 
latter  is  hung  below  the  pallet  arbor,  as  is  generally  the  case 
with  recoil  escapements  of  the  cheap  clocks,  and  if  it  is  too 
short  there  will  not  be  sufficient  power  applied  to  the  pendu- 
lum when  the  clock  gets  dirty  and  the  oil  dries,  in  which 
case  the  clock  will  stop  before  the  spring  runs  down. 

An  important  thing  to  look  after  when  repairing  is  in  the 
verge  wire  -and  loop  (the  slot  the  pendulum  rod  goes 
through).  After  the  clock  is  set  up  and  oiled,  put  it  on  a 
level  shelf;   have  a  special  adjusted  shelf  for  this  level  ad- 


THE    MODERN    CLOCK.  S9 

justing,  one  that  is  absolutely  correct.  Have  the  dial  off. 
If  the  beat  is  off  on  one  side,  so  that  it  bangs  up  heavily  on 
one  side  of  the  escape  wheel,  bend  the  verge  wire  the  same 
way.  That  will  reverse  the  action  and  put  it  in  beat. 
So  far  so  good — but  don't  stop  now.  Just  notice  whether 
if  that  shelf  were  tipped  forward  or  back,  as  perhaps  your 
customer's  may,  that  the  pendulum  should  still  hang  plumb 
and  free.  Now  if  the  top  of  your  clock  tips  forward,  the 
pendulum  ball  inclines  to  hang  out  toward  the  front.  We 
will  suppose  you  put  two  small  wedges  under  the  back  of  the 
case.  Now  notice  in  its  hanging  out  whether  the  pendulum 
rod  pinches  or  bears  in  the  throat  of  the  verge ;  or  if  it  tips 
back,  see  if  the  rod  hits  the  other  end  of  the  slot.  This 
verge  slot  should  be  long  enough,  with  the  rod  hanging  in 
the  middle  when  adjusted  to  beat  on  a  level,  to  admit  of  the 
clock  pitching  forward  or  back  a  little  without  creating  a 
friction  on  the  ends  of  the  slot.  This  little  loop  should 
be  open  just  enough  to  be  nice  and  free;  if  open  too  much, 
you  will  notice  the  pallet  fork  will  make  a  little  jump  when 
carrying  the  ball  over  by  hand.  This  is  lost  motion.  If  this 
little  bend  of  wire  is  not  parallel  it  may  be  opened  enough 
inside,  but  if  pitched  forward  a  little  it  will  bind  in  the  nar- 
rowest part  of  the  V  and  then  the  clock  will  stop.  The  clock 
beat  and  the  tipping  out  or  in  of  the  clock  case,  causing  a 
binding  or  bearing  of  the  pendulum  rod  in  this  verge  throat, 
does  more  towards  stopping  clocks  just  repaired  than  all 
other  causes. 

Putting  in  Beat. — To  put  a  clock  in  beat,  hang  the  clock 
in  such  a  position  that  when  the  pendulum  is  at  rest  one 
tooth  of  the  escape  wheel  will  rest  on  the  center  of  a  pallet 
stone.  Screwed  on  the  case  of  the  clock  at  the  bottom  of 
the  pendulum  there  is,  or  should  be,  an  index  marked  with 
degrees.  Now,  while  the  escape-wheel  tooth  is  resting  on 
the  pallet,  as  explained  above,  the  index  of  the  pendulum 
should  point  to  zero  on  the  index.    Move  the  pendulum  until 


90 


THE    MODERN    CLOCK. 


the  tooth  just  escapes  and  note  how  many  degrees  beyond 
zero  the  pendulum  point  is.  Say  it  escapes  2°  to  the  left; 
now  move  the  pendulum  until  the  next  tooth  escapes — it 
should  escape  2°  to  the  right.  But  let  us  suppose  it  does  not 
■escape  until  the  index  of  the  pendulum  registers  5°  to  the 
right  of  zero.  In  this  case  the  rod  attached  to  the  pallets 
must  be  bent  until  the  escape  wheel  teeth  escape  when  the 
pendulum  is  moved  an  even  number  of  degrees  to  the  right 
and  left  of  zero,  when  the  clock  will  be  in  beat. 

Close  Rating  with  Shot. — V^ery  close  rating  of  a  sec- 
onds' pendulum,  accompanied  by  records  in  the  book,  may 
be  got  with  the  nut  alone,  but  there  is  the  inconvenience  of 
stopping  the  clock  to  make  an  alteration.  This  may  be  avoid- 
ed by  having  a  small  cup  the  size  of  a  thimble  or  small  pill 
box  on  the  pendulum  top.  This  can  be  lifted  off  and  put 
back  without  disturbing  the  motion  of  the  pendulum.  In 
using  it  a  number  of  small  shot,  selected  of  equal  size,  are 
put  in,  say  60,  and  the  clock  brought  as  nearly  as  possible 
to  time  by  the  nut.  After  a  few  days  the  cup  may  be 
emptied  and  put  back,  when  on  further  trial  the  value  of  the 
60  shot  in  seconds  a  day  will  be  found.  This  value  divided 
by  60  will  give  the  value  of  a  single  shot,  by  knowing  which 
very  small  alterations  of  rate  may  be  made  with  a  definite 
approach  towards  accuracy,  and  in  much  less  time  than  by 
putting  in  or  taking  out  one  or  more  shot  at  random. 


CHAPTER  VI. 

TORSION  PENDULUMS  FOR  FOUR  HUNDRED  DAY  CLOCKS. 

As  this  pendulum  is  only  found  in  the  400-day,  or  annual 
wind,  or  anniversary  clocks  (they  are  known  by  all  of  these 
names),  it  is  best  to  describe  the  pendulum  and  movement 
together,  as  its  relations  to  the  work  to  be  done  may  be 
more  easily  perceived. 

Rotating  pendulums  of  this  ki|id — that  is,  in  which  the 
bob  rotates  by  the  twisting  of  the  suspension  rod  or  spring 
— will  not  bear  comparison  with  vibrating  pendulums  for  ac- 
curate time  keeping.  They  are  only  used  when  a  long 
period  between  windings  is  required.  Small  clocks  to  go 
for  twelve  months  with  one  winding  have  the  torsion  pen- 
dulum ribbons  of  flat  steel  about  six  inches  long,  making  15 
beats  per  minute.  The  time  occupied  in  the  beat  of  such  a 
pendulum  depends  on  the  power  of  the  suspending  ribbon 
to  resist  twisting,  and  the  weight  and  distance  from  the 
center  of  motion  of  the  bob.  In  fact,  the  action  of  the 
bob  and  suspending  ribbon  is  very  analogous  to  that  of  a 
balance  and  balance  spring. 

In  order  to  get  good  time  from  a  clock  of  this  character, 
it  should  be  made  with  a  dead-beat  escapement.  With  such 
an  escapement  there  is  no  motion  of  the  escape  wheel,  after 
the  tooth  drops  on  the  locking  face  of  the  pallet ;  the  escape 
wheel  is  dead  and  does  not  move  again  until  it  starts  to 
give  the  pallet  impulse.  This  style  of  an  escapement  allows 
the  pendulum  as  much  freedom  to  vibrate  as  possible,  as 
the  fork  in  one  form  of  this  escapement  may  leave  the 
pallet  pin  as  soon  as  the  latter  strikes  the  guard  pins,  as 
in  the  ordinary  lever  escapement  of  a  watch,  and  it  will 
remain  in  that  position  until  the  return  of  the  fork  unlocks 

91 


93 


THE     MODERN     CLOCK. 


the  escapement  to  receive  another  impulse.  B,  Fig.  17, 
represents  the  escape  wheel;  C,  the  pallet;  E,  pallet  staff; 
D,  the  pallet  pin  rivetted  on  to  the  pallet  staff  E,  which 
works  in  the  slot  or  fork  H;  this  fork  is  screwed  fast  to 

in 


L 


!=ii;iuMfj%Miii,m      ^:  — iMnmfipi,i,mii=> 


Fig.  17. 

the  spring.  The  spring  G  is  made  of  a  piece  of  flat  steel 
wire  and  looks  like  a  clock  hairspring  straightened  out.  G 
is  fast  to  the  collar  I  and  rests  on  a  seat  screwed  to  the 
plate  of  the  clock,  as  shown  at  P ;  the  spring  is  also  fast- 
ened to  the  pendulum  ball  O  with  screw?;  the  ball  makes 


THE     MODERN     CLOCK, 


93 


about  one  and  one-half  revolutions  each  beat,  which  causes 
the  spring  to  twist.  It  twists  more  at  the  point  S  than  it 
does  at  L;  as  it  twists  at  L  it  carries  the  fork  with  it,  so 
that  the  latter  vibrates  from  one  side  to  the  other^  similar 
to  a  fork  in  a  watch.  This  fork  H  carries  the  pin  D,  which 
is  fast  to  the  pallet  staff  E,  far  enough  to  allow  the  teeth 
to  escape. 


Fig.  18. 

In  the  most  common  form  of  this  escapement,  see  Fig. 
1 8,  the  fork  does  not  allow  the  pin  D  to  leave  the  slot  H, 
and  the  beat  pins  are  absent,  the  pendulum  not  being  as 
highly  detached  as  in  the  form  previously  mentioned.  In 
this  case  great  care  must  be  taken  to  have  the  edges  of  the 
slot,  which  slide  on  the  pallet  pin,  smooth,  parallel  and 
properly  beveled,  so  as  not  to  bind  on  the  pin.  The  pen- 
dulum ball  makes  from  eight  to  sixteen  vibrations  a  min- 
ute. Of  course  the  number  depends  upon  the  train  of  the 
clock. 

In  suspending  the  pendulum  it  is  necessary  to  verify  the 
drop  of  the  teeth  of  the  escape  wheel  as  follows :  The  pen- 
dulum is  suspended  and  the  locking  position  of  the  pallets 


94 


THE    MODERN    CLOCK. 


marked,  taking  as  a  guiding  point  the  long,  regulating 
screw,  which,  fixed  transversely  in  the  support,  serves  for 
adjusting  the  small  suspension  block.  An  impulse  of  about 
a  third  of  a  turn  is  given  to  the  pendulum  while  observing 
the  escap'ement.  If -the  oscillations  of  the  pendulum,  meas- 
ured on  the  two  sides,  taking  the  locking  point  as  the  base, 
are  symmetrical,  the  drop  is  also  equal,  and  the  rate  of  the 
clock  regular  and  exact ;  but  if  the  teeth  of  the  escape  wheel 
are  unlocked  sooner  on  one  side  than  on  the  other,  so  that 
the  pendulum  in  its  swing  passes  beyond  the  symmetrical 


Fig.  19. 


point  on  one  of  the  pallets  and  does  not  reach  it  on  the 
other,  it  is  necessary  to  correct  the  unequal  drop. 

The  suspension  block  B,  .Fig.  i8,  between  the  jaws  of 
which  the  steel  ribbon  is  pressed  by  two  screw^s,  has  a  lower 
cylindrical  portion,  which  is  fitted  in  a  hole  made  in  the 
seat,  and  is  kept  immovable  by  the  screw  A.  If  the  vibra- 
tion of  the  pendulum  passes  beyond  the  proper  point  on  the 
left  side,  it  is  necessary  to  loosen  A  and  turn  the  sus- 
pension block  slightly  to  the  right.  If  the  deviation  is 
produced  in  the  opposite  direction,  it  is  necessary  to  turn 


THE     MODERN     CLOCK, 


95 


it  to  the  left.  These  corrections  should  be  repeated  until 
the  drop  of  the  escape  wheel  teeth  on  the  pallets  is  exactly 
equal  on  the  two  sides.  As  the  drop  is  often  disturbed  by 
the  fact  that  the  long  thin  steel  ribbon  has  been  twisted 
in  cleaning,  taking  apart  or  handling  by  unskilled  persons 
before  coming  to  the  watchmaker,  it  is  desirable  to  test  the 
escapement  again,  when  the  clock  is  put  into  position  on 
the  premises  of  the  buyer. 

The  timing  adjustment  of  the  pendulum  is  effected  with 
the  aid  of  regulating  weights,  placed  on  the  ball.  By  mov- 
ing these  away  from  the  center  by  means  of  a  right  and 
left  hand  screw  on  the  center  of  the  disk  (see  Fig.  19), 


Fig.  20. 


the  centrifugal  force  is  augmented,  the  oscillations  .of  the 
pendulum  slackened,  and  the  clock  goes  slower.  The  con- 
trary effect  is  produced  if  the  weights  are  brought  nearer 
the  center.  In  one  form  of  ball  the  shifting  of  the  regu- 
lating weights  is  accomplished  by  a  compensating  spring  of 
steel  and  brass  like  the  rim  of  a  watch  balance.  Fig.  20. 

If  necessary  to  replace  the  pendulum  spring,  the  adjust- 
ment is  commenced  by  shortening  or  lengthening  the  steel 
ribbon  to  a  certain  extent.  For  this  purpose  the  end  of 
the  spring  is  allowed  to  project  above  the  suspension  block 
as  a  reserve  until  adjustment  has  been  completed,  when  it 
may  be  cut  off.  If  the  space  between  the  ball  and  the  bot- 
tom of  the  case,  or  the  bottom  of  the  movement  plates,  does 


g6  THE     MODERN     CLOCK. 

not  allow  of  attaining  this  end,  it  is  necessary  to  increase 
or  decrease  the  weight  of  the  disk,  adding  one  or  several 
plates  of  metal  in  a  depression  made  in  the  under  side  of 
the  ball,  and  removing  the  plates  screwed  to  it,  which  are 
too  light. 

There  are  some  peculiarities  of  the  trains  of  these  clocks. 
The  cannon  pinion  is  provided  with  a  re-enforcing  spring, 
serving  as  guide  to  the  dial  work,  on  which  it  exercises  a 
sufficient  pressure  to  assure  precise  working.  The  pressure 
of  this  spring  is  important,  because  if  the  dial  work  presses 
too  hard  on  the  pinion  of  the  minute  wheel,  the  latter  en- 
gaging directly  with  the  escape  wheel,  would  transmit  to  the 
latter  all  the  force  employed  in  setting  the  hands.  The 
teeth  of  the  escape  wheel  would  incur  damage  and  the  con- 
sequent irregularity  or  even  stopping  of  the  clock  would 
naturally  follow. 

In  order  that  it  may  run  for  so  long  a  time,  the  motive 
force  is  transmitted  through  the  train  by  the  intervention 
of  three  supplementary  wheels  between  the  minute  wheel 
and  the  barrel,  in  order  to  avoid  the  employment  of  too  large 
a  barrel;  the  third  wheel  is  omitted;  the  motion  work  is 
geared  immediately  with  the  arbor  of  the  escape  wheel. 
It  is  evident  that  the  system  of  the  three  intermediate 
wheels,  of  which  we  have  spoken,  requires  for  the  motive 
force  a  barrel  spring  much  stronger  than  that  of  ordinary 
clocks. 

The  points  which  we  have  noticed  are  of  the  most  im- 
portanc-e  with  reference  to  the  repair  and  keeping  in  order 
of  an  annual  clock.  It  very  often  happens  that  when  the 
repairer  does  not  understand  these  clocks,  irregularities  are 
sought  for  where  they  do  not  exist.  The  pivot  holes  are 
bushed  and  the  depthings  altered,  when  a  more  intelligent 
examination  would  show  that  the  stopping,  or  the  irregular 
rate  of  the  clock,  proceeds  only  from  the  condition  of  the 
escapement.     Unless,  however,  they  are  perfectly  adjusted, 


THE     MODERN     CLOCK.  97 

a  variation  of  five  minutes  a  week  is  a  close  rate  for  them, 
and  most  of  those  in  use  will  vary  still  more. 

Annual  clocks  are  enjoying  an  increased  favor  with  the 
public;  their  good  qualities  allow  confidence,  the  rate  being 
quite  regular  when  in  proper  order.  They  are  suitable  for 
offices ;  their  silent  running  recommends  them  for  the  sick 
chamber,  and  the  subdued  elegance  of  their  decoration 
causes  the  best  of  them  to  be  valued  ornaments  in  the  home. 


-gahd  e:  Loo^  ih 

i^i2u't:ikRirit§''m  'AnGVtLkR  MEAsuREMEWt— lidw'--  Tcf-^^^i) 
iv'^-  DRAWINGS.  .i^cirriGd:) 

"'We  now  come  to  a  point  at  which,  if  we  are  to  keep  our 
pendulum  vibrating,  we  must  apply  power  to  it,  evenly,  ac- 
curately and  in  small  doses.  In  order  to  do  this  convenient- 
ly we  must  store  up  energy  by  raising  a  weight  or  winding 
a  spring  and  allow  the  weight  to  fall  or  the  spring  to  un- 
wind very  slowly,  say  in  thirty  hours  or  in  eight  days.  This 
brings  about  the  necessity  of  changing  rotary  motion  to 
reciprocating  motion,  and  the  several  devices  for  doing  this 
are  called  "escapements"  in  horology,  each  being  further 
designated  by  the  names  of  their  inventors,  or  by  some 
peculiarity  of  the  devices  themselves ;  thus,  the  Graham  is 
also  called  the  dead  beat  escapement;  Lepaute's  is  the  pin 
wheel;  Dennison's  in  its  various  forms  is  called  the  gravity; 
Hooke's  is  known  as  the  recoil ;  Brocot's  as  the  visible 
escapement,  etc. 

The  Mechanical  Elements. — We  shall  understand  this 
subject  more  clearly,  perhaps,  if  we  first  separate  these 
mechanical  devices  into  their  component  parts  and  consider 
them,  not  as  parts  of  clocks,  but  as  various  forms  of  levers, 
which  they  really  are.  This  is  perhaps  the  best  place  to- 
consider  the  levers  we  are  using  to  transmit  the  energy 
to  the  pendulum,  as  at  this  point  we  shall  find  a  greater  va- 
riety of  forms  of  the  lever  than  in  any  other  place  in  the 
clock,  and  we  shall  have  less  difficulty  in  understanding  the 
methods  of  calculating  for  time  and  power  by  a  thorough 
preliminary  understanding  of  leverage  and  the  peculiarities 
of  angular  or  circular  motion. 

9S 


THE     MODERN     CLOCK. 


99 


If  we  take  a  bar,  A,  Fig.  21,  and  place  under  it  a  ful- 
crum, B,  then  by  applying  at  C  a  given  force,  we  shall  be 
able  to  lift  at  D  a  weight  whose  amount  will  be  governed 
by  the  relative  distances  of  C  and  D  from  the  fulcrum  B. 


C 


Fig.  21. 

If  the  distance  CB  is  four  times  that  of  BD,  then  a  force 
of  10  pounds  at  C  will  lift  40  pounds  at  D,  for  one-fourth 
of  the  distance  through  which  C  moves,  minus  the  power 
lost  by  friction.  The  reverse  of  this  is  also  true;  that  is, 
it  will  take  40  pounds  at  D  to  exert  a  force  of  10  pounds 


-  Fig.  22. 

at  C  and  the  10  pounds  would  be  lifted  four  times  as  far 
as  the  40  pound  weight  was  depressed. 

If  instead  of  a  weight  we  substitute  other  levers.  Fig.  22, 
the  result  would  be  the  same,  except  that  we  should  move 
the  other  levers  until  the  ends  which  were  in  contact 
slipped  apart. 

II 
^'  J  A 


^D 


Fig.  23. 


If  we  divide  our  lever  and  attach  the  long  end  to  one 
portion  of  an  axle,  as  at  A,  Fig.  23,  and  the  short  end  to 
another  part  of  it  at  B,  the  result  will  be  the  same  as  long 


lOO  THE     MODERN     CLOCK. 

as  the  proportions  of  the  lever  are  not  changed.  It  will 
still  transmit  power  or  impart  motion  according  to  the 
relative  lengths  of  the  two  parts  of  the  lever.  The  capacity 
of  our  levers,  Fig.  22,  will  be  limited  by  that  point  at  which 
the  ends  of  the  levers  will  separate,  because  they  are  held 
at  the  points  of  the  fulcrums  and  constrained  to  move  in 
circles  by  the  fulcrums.  If  we  put  more  levers  on  the 
same  axles,  so  spaced  that  another  set  will  come  into  action 
as  the  first  pair  are  disengaged,  we  can  continue  our  trans- 
mission of  power.  Fig.  24;  and  if  we  follow  this  with  still 


Fig.  24. 

others  until  we  can  add  no  more  for  want  of  room  we  shall 
have  wheels  and  pinions,  the  collection  of  short  levers  form- 
ing the  pinion  and  the  group  of  long  levers  forming  the 
wheel,  Fig.  25.  Thus  every  wheel  and  pinion  mounted  to- 
gether on  an  arbor  are  simply  a  collection  of  levers,  each 
wheel  tooth  and  its  corresponding  pinion  leaf  forming  one 
lever.  This  explains  why  the  force  decreases  and  the  mo- 
tion increases  in  proportion  to  the  relative  lengths  of  the 
radii  of  the  wheels  and  pinions,  so  that  eight  or  ten  turns  of 
the  barrel  of  a  clock  will  run  the  escape  wheel  all  day. 

We  now  come  to  the  verge  or  anchor,  and  here  we  have 
the  same  sort  of  lever  in  a  different  form;  the  verge  wire, 
which  presses  on  the  pendulum  rod  and  keeps  it  going  is 
the  long  arm  of  our  lever,  but  instead  of  many  there  is  only 
one.  The  short  arm  of  our  lever  is  the  pallet,  and  there 
are  two  of  these.  Therefore  we  have  a  form  of  lever  in 
which  there  is  one  long  arm  and  two  short  ones ;  but  as  the 
two  are  never  acting  at  the  same  time  they  do  not  interfere 
with  each  other. 


TJIE     MODERN     CLOCK. 


Ol 


These  systems  of  levers  have  another  advantage,  which 
is  that  one  arrri  need  not  be  on  the  opposite  side  of  the  ful- 


ff 


Fii-.  25. 


crum  from  the  other.  It  may  be  on  the  same  side  as  in  the 
verge  or  at  any  other  convenient  point.  This  enables  us 
to  save  space  in  arranging  our  trains,  as  such  a  collection 


I02  THE     MODERN     CLOCK. 

of  wheels  and  pinions  is  called,  by  placing  them  in  any  ,po- 
sition  which,  on  account  of  other  facts,  may  seem  desirable. 

Peculiarities  of  Angular  Motion. — Now  our  collec- 
tions of  levers  must  move  in  certain  directions  in  order  to 
be  serviceable  and  in  order  to  describe  these  things  prop- 
erly, we  must  have  names  for  these  movements  so  that  we 
can  convey  our  thoughts  to  each  othei'.  Let  us  see  how 
they  move.  They  will  not  move  vertically  (up  or  down) 
or  horizontally  (sidewise),  because  we  have  taken  great 
pains  to  prevent  them  from  doing  so  by  confining  the  cen- 
tral bars  of  our  levers  in  a  fixed  position  by  making  pivots 
on  their  ends  and  fitting  them  carefully  into  pivot  holes  in 
the  plates,  so  that  they  can  move  only  in  one  plane,  and 
that  movement  must  be  in  a  circular  direction  in  that  pre- 
determined plane.  Consequently  we  must  designate  any 
movement  in  terms  of  the  portions  of  a  circle,  because  that 
is  the  only  way  they  can  move. 

These  portions  of  a  circle  are  called  angles,  which  is  a 
general  term  meaning  always  a  portion  of  a  circle,  meas- 
ured from  its  center ;  this  will  perhaps  be  plainer  if  we  con- 
sider that  whenever  we  want  to  be  specific  in  mentioning 
any  particular  size  of  angle  we  must  speak  of  it  in  degrees, 
minutes  and  seconds,  which  are  the  names  of  the  standard 
parts  into  which  a  circle  is  divided.  Now  in  every  circle, 
large  or  small,  there  are  360  degrees,  because  a  degree  is 
I -360th  part  of  a  circle,  and  this  measurement  is  always 
from  its  center.  Consequently  a  degree,  or  any  angle  com- 
posed of  a  number  of  degrees,  is  always  the  same,  because, 
being  measured  from  its  center,  such  measurements  of  any 
two  circles  will  coincide  as  far  as  they  go.  If  we  draw 
two  circles  having  their  centers  over  each  other  at  A,  Fig. 
26,  and  take  a  tenth  part  of  each,  we  shall  have  36o°-^-io:= 
36°,  which  we  shall  mark  out  by  drawing  radial  lines  to 
the  circumference  of  each  circle,  and  we  shall  find  this  to 
be  true:  the  radii  of  the  smaller  circle  AB   and  AC  will 


THE     MODERN     CLOCK. 


103 


coincide  M^ith  the  radii  AD  and  AE  as  far  as  they  go.  This 
is  because  each  is  the  tenth  part  of  its  circle,  measured  from 
its  center.  Now  that  portion  of  the  circumference  of  the 
circle  BC  will  be  smaller  than  the  same  portion  DE  of  the 
larger  circle,  but  each  will  be  a  tenth  part  of  its  ozvn  circle, 
although  they  are  not  the  same  size  when  measured  by  a 
rule  on  the  circumference.  This  is  a  point  which  has 
bothered  so  many  people  w^hen  taking  up  the  study  of  an- 
gular measurement  that  we  have  tried  to  make  it  absurdly 


clear.  An  angle  never  means  so  many  feet,  inches  or 
millimeters ;  it  always  means  a  portion  of  a  circle,  measured 
from  the  center.  ^  v  ,ji":^i 

There  is  one  feature  about  these  angular  (of  circular) 
measurements  that  is  of  great  convenience,  which  is  that 
as  no  definite  size  is  mentioned,  but  only  proportionate 
sizes,  the  description  of  the  machine  described  need  not  be 
changed  for  any  size  desired,  as  it  will  fit  all  sizes.  It  thus 
becomes  a  flexible  term,  like  the  fraction  ''one-half,"  chang- 
ing its  size  to  suit  the  occasion.  Thus,  one-half  of  300,000 
bushels  of  wheat  is  150,000  bushels;  one-half  of  10  bush- 
els is  5  bushels ;  one-half  of  one  bushel  is  two  pecks ;  yet 
each  is  one-half.     It  is  so  with  our  angles. 

There  are  some  other  terms  which  we  shall  do  well  to 
investigate  before  we  leave  the  subject  of  angular  meas- 


I04 


THE     MODERN     CLOCK. 


urements,  which  are  the  relations  between  the  straight  and 
curved  lines  we  shall  need  to  study  in  our  drawings  of  the 
various  escapements.  A  radius  (plural  radii)  is  a  straight 
line  drawn  from  the  center  of  a  circle  to  its  circumference. 
A  tangent  is  a  straight  line  drawn  outside  the  circum- 
ference, touching  (but  not  cutting)  it  at  right  angles  (90 
degrees)  to  a  radius  drawn  to  the  point  of  tangency  (point 
where  it  touches  the  circumference).  A  general  misun- 
derstanding of  this  term  (tangent)  has  done  much  to  hinder 
a  proper  comprehension  of  the  writers  who  have  attempted 
to  make  clear  the  mysteries  of  the  escapements.  Its  im- 
portance will  be  seen  when  we  recollect  that  about  the  first 
thing  we  do  in  laying  out  an  escapement  is  to  draw  tangents 
to  the  pitch  circle  of  the  escape  wheel  and  plant  our  pallet 
center  where  these  tangents  intersect  on  the  line  of  cen- 
ters. They  should  always  be  drawn  at  right  angles  to  the 
radii  which  mark  the  angles  we  choose  for  the  working 
portion  of  our  escape  wheel.  If  properly  drawn  we  shall 
find  that  the  pallet  arbor  will  then  locate  itself  at  the  cor- 
rect distance  from  the  escape  wheel  center  for  any  desired 
angle  of  escapement.  We  shall  also  discover  that  it  will 
take  a  different  center  distance  for  every  different  angle 
and  yet  each  different  position  will  be  the  correct  one  for 
its  angle,  Fig.  27. 

Because  an  angle  is  always  the  same,  no  matter  how  far 
from  the  center  the  radii  defining  it  are  carried,  we  are 
able  to  work  conveniently  with  large  drawing  instruments 
on  small  drawings.  Thus  we  can  use  an  eight  or  ten  inch 
protractor  in  laying  off  our  angles,  so  as  to  get  the  degrees 
large  enough  to  measure  accurately,  mark  the  degrees  with 
dots  on  our  paper  and  then  draw  our  lines  with  a  straight 
edge  from  the  center  towards  the  dots,  as  far  as  we  wish 
to  go.  Thus  we  can  lay  off  the  angles  on  a  one-inch 
escape  wheel  with  a  ten-inch  protractor  more  easily  and 
correctly  than  if  we  were  using  a  smaller  instrument. 


THE     MODERN     CLOCK.  I05 


lA 

/f\ 

/     .     \ 

/        1         \ 

T/     1      \ 

/    :   V 

/         'N        ^ 

/  /  ^'^-  ^  ^^ 

/  /  -','^^^x\  ^ 

//;cin''t-~->^>.\\ 

/ 

/  ■i!'\              \             '             /             >'^-^.     \ 

^      s 

\           \         \         ,          '          /            /               ^    \ 
\                   \        '        /         /          /               ^          "< 

^  \  \  \  i  /  /  /    /     A 

/ 

s 

\ 
\ 
\ 

^v^- 

I 

1 

\ 

/ 

\P 

/ 

\ 

/ 

\ 

/ 

\ 

'                            / 

\ 

\ 

•                            / 

\ 

V 

! 

\  I 

! 

I 
-  -I 

IB 

Fig.  27, 


I06  THE     MODERN     CLOCK. 

Another  thing  which  will  help  us  in  understanding  these 
drawings  is  that  the  effective  length  of  a  lever  is  its  dis- 
tance from  the  center  to  the  working  point,  measured  in 
a  straight  line.  Thus  in  a  pallet  of  a  clock  the  distance 
of  the  pallets  from  the  center  of  the  pallet  arbor  is  the 
effective  length  of  that  arm  of  the  lever,  no  matter  how 
it  may  be  curved  for  ornament  or  for  other  reasons. 

The  lines  and  circles  drawn  to  enable  us  to  take  the 
necessary  measurements  of  angles  and  center  distances  are 
called  "'construction  lines"  and  are  generally  dotted  on 
the  paper  to  enable  us  to  distinguish  them  as  lines  for 
measurement  only,  while  the  lines  which  are  intended  to 
define  the  actual  shapes  of  the  pieces  thus  drawn  are  solid 
lines.  By  observing  this  distinction  we  are  enabled  to 
show  the  actual  shapes  of  the  objects  and  all  their  angular 
measurements  clearly  on  the  one  drawing. 

With  these  explanations  the  student  should  be  able  to 
read  clearly  and  correctly  the  many  drawings  which  fol- 
low, and  we  will  now  turn  our  attention  to  the  escape- 
ments. In  doing  this  we  shall  meet  with  a  constant  use 
of  certain  terms  which  have  a  peculiar  and  special  mean- 
ing when  applied  to  escapements. 

The  Lift  is  the  amount  of  angular  motion  imparted  to 
the  verge  or  anchor  by  the  teeth  of  the  escape  wheel  press- 
ing against  the  pallets  and  pushing  first  one  and  then  the 
other  out  of  the  way,  so  that  the  escape  wheel  teeth  may 
pass.  According  as  the  angular  motion  is  more  or  less 
the  "Hft"  is  said  to  be  greater  or  less;  as  this  motion  is 
circular,  it  must  be  expressed  in  degrees.  The  lifting 
planes  are  those  surfaces  which  produce  this  motion;  in 
clocks  with  pendulums  the  lifting  planes  are  generally  on 
the  pallets,  being  those  hard  and  smoothly  polished  sur- 
faces over  which  the  points  of  the  escape  wheel  teeth  slide 
in  escaping.  In  lever  escapements  the  lifting  planes  are 
frequently  on  the  escape  wheel,  the  pallets  being  merely 


THE     MODERN     CLOCK. 


07 


round  pins.  Such  an  escape  wheel  is  said  to  have  club 
teeth,  as  distinguished  from  the  pointed  teeth  used  when 
the  Hfting  planes  are  on  the  pallets.  In  the  cylinder 
escapement  the  lifting  planes  are  on  the  escape  wheel; 
they  are  curved  instead  of  being  straight;  and  there  is  but 
one  pallet,  which  is  on  the  lip  of  the  cylinder.  In  the 
forms  of  lever  escapement  used  in  watches  and  some 
clocks  the  lift  is  divided,  part  of  the  lifting  planes  being 
also  on  the  pallets;  in  this  case  both  sets  of  planes  are 
shorter  than  if  they  were  entirely  on  one  or  the  other,  but 
they  must  be  long  enough  so  that  combined  they  will  pro- 
duce the  requisite  amount  of  angular  motion  of  the  pallets, 
so  as  to  give  the  requisite  impulse  to  the  pendulum  or  bal- 
ance. 

The  Drop  is  the  amount  of  circular  motion,  measured 
in  degrees,  which  the  escape  wheel  has  from  the  instant 
the  tooth  escapes  from  one  pallet  to  that  point  at  which  it 
is  stopped  by  the  other  pallet  catching  another  tooth.  Dur- 
ing this  period  the  train  is  running  down  without  impart- 
ing any  power  to  the  pendulum  or  balance,  hence  the  drop 
is  entirely  lost  motion.  We  must  have  it,  however,  as  it 
requires  some  time  for  the  other  pallet  to  move  far  enough 
within  the  pitch  circle  of  the  escape  wheel  to  safely  catch 
and  stop  the  next  tooth  under  all  circumstances.  It  is  the 
freedom  and  safety  of  the  working  plan  of  our  escape- 
ment, but  it  is  advisable  to  keep  the  drop  as  small  as  is 
possible  with  safe  locking. 

The  Lock  is  also  angular  motion  and  is  measured  in 
degrees  from  the  center  of  the  pallet  arbor.  It  is  the 
distance  which  the  pallet  has  moved  inside  of  the  pitch 
circle  of  the  escape  wheel  before  being  struck  by  the  escape 
wheel  tooth.  It  is  measured  from  the  edge  of  the  lifting 
plane  to  the  point  of  the  tooth  where  it  rests  on  the  lock- 
ing face  of  the  pallet.     A  safe  lock  is  necessary  in  order 


I08  THE     MODERN    CLOCK. 

to  prevent  the  points  of  the  escape  wheel  teeth  butting 
against  the  lifting  planes,  stopping  the  clock  and  injuring 
the  teeth.  We  want  to  point  out  that  from  the  instant 
of  escaping  to  the  instant  of  locking  we  have  the  two  parts 
of  our  escapement  propelled  by  different  and  entirely  sep- 
arate forces  and  moving  at  different  speeds.  The  pallets, 
after  having  given  impulse  to  the  pendulum,  are  controlled 
by  the  pendulum  and  moved  by  it;  in  the  case  of  a  heavy 
pendulum  ball  at  the  end  of  a  40-inch  lever,  this  control 
is  very  steady,  powerful  and  quite  slow.  The  escape 
wheel,  the  lightest  and  fastest  in  the  train,  is  driven  by 
the  weight  or  spring  and  moves  independently  of  the 
pallets  during  the  drop,  so  that  safe  locking  is  important. 
It  should  never  be  too  deep,  as  it  would  increase  the  swing 
of  the  pendulum  too  much;  this  is  especially  true  with 
short  and  light  pendulums  and  strong  mainsprings. 

The  Run. — After  locking  the  pallet  continues  to  move 
inward  towards  the  escape  wheel  center  as  the  pendulum 
continues  its  course,  and  the  amount  of  this  motion,  meas- 
ured in  degrees  from  the  center  of  the  pallet  arbor,  is 
called  the  run. 

When  the  escapement  is  properly  adjusted  the  lifting 
planes  are  of  the  same  length  on  both  pallets,  when  they 
are  measured  in  degrees  of  motion  given  to  the  pallet  ar- 
bor. They  may  or  may  not  be  equal  in  length  when 
measured  by  a  rule  on  the  faces  of  the  pallets.  There 
should  also  be  an  equal  and  safe  lock  on  each  pallet,  as 
measured  in  degrees  of  movement  of  the  pallet  arbor. 
The  run  should  also  be  equal. 

The  reason  why  one  lifting  plane  may  be  longer  than 
the  other  and  still  give  the  same  amount  of  lift  is  that 
some  escapements  are  constructed  with  unequal  lockings, 
so  that  one  radius  is  longer  than  the  other,  and  this,  as 
we  explained  at  length  in  treating  of  angles.  Fig.  26,  would 
make  a  difference  in  the  length  of  arc  traversed  by  the 
longer  arm  for  the  same  angle  of  motion. 


CHAPTER   VIII. 

THE  GRAHAM   OR  DEAD  BEAT  ESCAPEMENT. 

This  escapement  is  so  called  because  the  escape  wheel 
remains  "dead"  (motionless)  during  the  periods  between 
the  impulses  given  to  the  pendulum.  It  is  the  original  or 
predecessor  of  the  well  known  detached  lever  escapement 
so  common  in  watches,  and  it  is  surprising  how  many 
watchmakers  who  are  fairly  well  posted  on  the  latter  form 
exhibit  a  surprising  ignorance  of  this  escapement  as  used 
in  clocks.  It  has  like  the  latter  a  "lock,"  "lift"  and  "run" ; 
the  only  difference  being  that  it  has  no  "draw,"  the  control 
by  the  verge  wire  rendering  the  draw  unnecessary. 

It  may  be  made  to  embrace  any  number  of  teeth  of  the 
escape  wheel,  but,  owing  to  the  peculiarities  of  angular 
motion  referred  to  in  the  last  chapter,  see  Fig.  26,  B  C,  D  E, 
the  increased  arcs  traveled  as  the  pallet  arms  lengthen  in- 
troduce elements  of  friction  which  counterbalance  and  in 
some  cases  exceed  the  advantage  gained  by  increasing  the 
length  of  the  lever  used  to  propel  the  pendulum.  Similarly, 
the  too  short  armed  escapements  were  found  to  cause  in- 
creased difficulty  from  faulty  fitting  of  the  pivots  and  their 
holes,  and  other  errors  of  workmanship,  which  errors  could 
not  be  reduced  in  the  same  proportion  as  the  arms  were 
shortened,  so  that  it  has  been  determined  by  practice  that  a 
pallet  embracing  ninety  degrees,  or  one-fourth  of  the  cir- 
cumference of  the  escape  wheel,  offers  perhaps  the  best 
escapement  of  this  nature  that  can  be  made.  Therefore  the 
factories  generally  now  make  them  in  this  way.  But  as 
many  clocks  are  coming  in  for  repair  with  greater  or  less 
5ircs  of  escapement  and  the  repairers  must  fix  them  satis- 

109 


no  THE     MODERN     CLOCK. 

factorily,  we  will  begin  at  the  beginning  by  explaining  how 
to  make  the  escapement  of  any  angle  whatever,  from  one 
tooth  up  to  140  degrees,  or  nearly  half  of  the  escape  wheel. 

It  is  quite  a  common  thing  for  some  workmen  to  imagine 
that  in  making  an  escapement,  the  pallets  ought  to  take 
in  a  given  number  of  teeth,  and  that  the  number  which  they 
suppose  to  be  right  must  not  be  departed  from;  but  there 
seems  to  be  no  rule  that  necessarily  prescribes  any  number 
of  teeth  to  be  used  arbitrarily.  The  nearer  that  the  center  of 
motion  of  the  pallets  is  to  the  center  of  the  escape  wheel,  the 
less  will  be  the  number  of  teeth  that  will  be  embraced  by  the 
pallets.  Fig.  28  is  an  illustration  of  the  distances  between 
the  center  of  motion  of  the  pallets  and  the  center  of  the 
wheel  required  for  3,  5,  7,  9  and  11  teeth  in  a  wheel  of  the 
same  size  as  the  circle;  but  although  we  have  adopted 
these  numbers  so  as  to  make  a  symmetrical  diagram,  any 
other  numbers  that  may  be  desirable  can  be  used  with  equal 
propriety.  All  that  is  necessary  to  be  done  to  find  the 
proper  center  of  motion  of  the  pallets  is  first  to  determine 
the  number  of  teeth  that  are  to  be  embraced,  and  draw 
lines  (radii)  from  the  points  of  the  outside  ones  of  the 
number  to  the  center  of  the  wheel,  and  at  right  angles  to 
these  lines  draw  other  two  lines  (tangents),  and  the  point 
where  they  intersect  each  other  on  the  line  of  centers  will  be 
the  center  of  motion  of  the  pallets. 

It  will  be  seen  by  the  diagram.  Fig.  28,  that  by  this 
method  the  distance  between  the  centers  of  motion  of  the 
pallets  and  that  of  the  scape-wheel  takes  care  of  itself  for  a 
given  number  of  teeth  and  that  it  is  greater  when  eleven 
and  one-half  teeth  are  to  be  embraced  than  for  eight  or  for 
a  less  number.  These  short  pallet  arms  are  imagined  by 
some  workmen  to  be  objectionable,  on  the  supposition  that 
it  will  take  a  heavier  weight  to  drive  the  clock;  but  it  can 
easily  be  shown  that  this  objection  is  altogether  imaginary. 
Now,  bearing  in  mind  the  principles  of  leverage,  if  the  dis- 
tance between  the  pallets  and  escape  wheel  centers  is  very 


THE     MODERN     CLOCK. 


Ill 


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t/    '    \ 


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N       '.      \      i      / 


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io  tnrjdPnB  £iix3  sfli 

soriEjcia^T  lo  JnnomL 

3rfJ  soncV^rb  biJxs  orf.i 

oril  io  2oni>tQ  ^nijlool  '  ! 

fjfl:^  ni  nHlIrjbnec.  [        i 

otirjp  ai  ialffiq  srfj  io  snBlq  ^nr}B 
jfiJ   no.  gj?5i  ji  3Dni2   nrr.c  fi^^'^s. 
bnsq  31? 

•vt^d  norloHi  5rh  rri  '7"':: 


112  THE     MODERN     CLOCK. 

long,  as  in  Graham's  plan,  in  which  the  pallets  embraced 
138°  of  the  escape  wheel,  the  value  of  the  impulse  received 
from  the  scape-wheel  and  communicated  through  the  pallets 
to  the  pendulum  is  no  doubt  greater  with  a  proper  length  of 
verge  wire,  for,  the  lifting  planes  being  longer,  the  leverage 
is  applied  to  the  pendulum  for  a  longer  arc  of  its  vibration, 
yet  we  must  not  suppose  that  from  this  fact  the  clock  will  go 


A 

Fig.  29.    Note  the  diflference  ia  length  of  arc  for  the  same  angle. 

with  less  weight,  for  it  is  easy  to  see  that  the  longer  the 
pallet-arms  are  the  greater  will  be  the  distance  the  teeth 
of  the  escape  wheel  will  have  to  move  (run)  on  the  circular 
part  of  the  pallets.  See  Fig.  29.  The  extra  amount  of 
friction,  and  the  consequent  extra  amount  of  resistance 
offered  to  the  pendulum,  caused  by  the  extra  distance  the 
points  of  the  teeth  run  on  the  circular  locking  planes  of  the 
pallets  and  back  again,  destroys  all  the  value  of  the  extra 
amount  of  impulse  given  to  the  pendulum  in  the  first  in- 
stance by  means  of  the  long  arms  of  the  pallets.  The  escape 
wheel  tooth  restinjy  on  the  locking  plane  of  the  pallet  is  quite 
var-able  in  its  effective  action,  and  since  it  rests  on  the 
pallet  during  a  part  of  each  swing  of  the  pendulum  and  the 
pendulum  is  called  on  to  move  the  pallet  back  and  forth 
under  the  tooth,  any  change  in  the- friction  between  the  tooth 
and  pallet  is  felt  by  the  pendulum  and  when  the  clock  gets 


THE     MODERN     CLOCK.  II3 

dirty  and  the  friction  between  the  tooth  and  pallet  is  in- 
creased, the  rate  of  the  clock  gets  slow,  as  the  friction  holds 
the  pendulum  from  moving  as  fast  as  it  would  without 
friction.  Now,  as  this  friction  increases  by  dirt  and  thick- 
ening of  the  oil,  all  these  forms  of  escapements  are  subject 
to  changes  and  so  change  the  clock's  rate.  An  increase  of 
the  driving  weight,  or  force  of  the  mainspring,  of  clocks 
with  dead-beat  escapements  always  tends  to  make  their  rate 
slow,  from  the  action  mentioned. 

It  is  for  this  reason  that  moderately  short  arms  are  used 
in  clocks  having  dead-beat  escapements  of  modern  con- 
struction. Most  of  the  first-class  modern  makeri  of  astro- 
nomical clocks  only  embrace  seven  and  one-half  tectli,  en  a 
30-tooth  wheel,  with  the  centers  of  motion  of  the  pallets  and 
scape-wheel  proportionately  nearer,  as  it  can  be  mathe- 
maticallv  demonstrated  that  with  the  pallets  embracing  an 
arc  of  90°  the  application  of  the  power  to  the  pendulum  is  at 
right  angles  to  the  rod  and  therefore  is  most  effective. 

To  Draw  the  Escapement. — In  order  to  make  the  mat- 
ter clearer  we  show  in  Fig.  30  the  successive  stages  of 
drawing  an  escapement  and  also  the  completed  work  in 
Figs.  32  and  33  embracing  different  numbers  of  teeth.  Draw 
a  line,  A  B,  Fig.  30,  to  serve  as  a  basis  for  measurements. 
With  a  compass  draw  from  some  point  C  on  this  line  a 
circle  to  represent  the  diameter  of  our  escape  wheel.  Now 
we  shall  require  to  know  how  many  teeth  there  will  be  in 
our  escape  wheel.  There  may  be  60,  40,  33,  32,  30,  or  any 
other  number  we  desire  to  give  it ;  seconds  pendulums  gen- 
erally have  30  teeth  in  this  wheel,  because  this  allows  the 
second  hand  to  be  mounted  directly  on  the  escape  wheel 
arbor  and  thus  avoids  complications.  We  divide  the  number 
of  degrees  in  a  circle  (360)  by  the  number  of  teeth  we  have 
selected,  say  30.  360 -f-  30  =  12°  for  each  tooth  and  space. 
One-fourth  of  360°  equals  90°  and  one-fourth  of  30  teeth 
equals  seven  and  one-half  teeth ;    each  tooth   equaling   12 


"4 


THE    MODERN    CLOCKo 


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Fig.  30, 


THE     MODERN     CI>OCK.  II5 

degrees,  we  have  12  X  7  =  84°>  which  gives  us  six  degrees 
for  drop,  to  ensure  the  safety  of  our  actions. 

We  now  take  90°  and,  dividing  it,  set  off  45°  each  side  of 
our  center  line  and  draw  radii,  R,  from  the  center  to  the  cir- 
cumference of  our  circle ;  this  marks  the  beginnings  of  our 
pallets.  Now  to  find  our  pallet  center  distance  we  draw 
tangents,  T  (at  right  angles),  from  the  ends  of  these  radii 
toward  the  line  of  centers.  The  point  where  they  intersect 
on  the  line  of  centers  is  the  pallet  center. 

Now  we  must  determine  how  much  motion  we  are  going 
to  give  our  pendulum,  so  that  we  can  give  the  proper  lift  to 
our  pallets.  Four  degrees  of  swing  is  usual  for  a  seconds 
pendulum,  so  we  will  take  four  degrees  and,  dividing  it,  give 
two  degrees  of  lift  to  each  pallet.  To  do  this  we  draw  a  line 
two  degrees  inside  the  tangent,  T  (towards  the  escape  wheel 
center),  from  our  pallet  center  on  the  entering  pallet  side 
and  another  line  from  the  pallet  center  two  degrees  outside 
of  the  tangent,  T,  on  the  exit  pallet  side.  Next,  from  the 
pallet  center  we  draw  arcs  of  circles  cutting  the  tangents, 
T,  and  the  radii,  R,  where  they  intersect;  this  gives  us  the 
locking  planes  on  which  the  teeth  of  the  escape  wheel  "run" 
(slide)  during  the  excursions  of  the  pendulum,  if  the 
escapement  is  to  have  unequal  lockings ;  if  the  lockings  are 
to  be  equidistant  (if  the  pallet  arms  are  to  be  of  equal  length) 
the  arc  for  the  entering  pallet  is  drawn  three  degrees  below 
(outside)  the  radius,  R,  while  that  on  the  exit  pallet  is 
drawn  three  degrees  above  (inside)  the  exit  radius.  Finally 
the  lifting  planes  are  drawn  from  the  intersection  of  the  arcs 
of  circles  struck  from  the  pallet  center  with  their  tangents, 
T,  to  the  lines,  marking  the  limits  of  the  lift,  two  degrees 
away.  These  lifting  planes  should  be  at  an  angle  of  60° 
from  the  radii,  R,  and  as  a  tangent  is  always  at  right  angles 
(90°)  to  its  radius,  they  are  consequently  at  30°  to 
the  tangents  running  to  the  pallet  center.  Thus  we  can 
measure  these  angles  from  either  the  escape  wheel  or  the 
pallet  center,  as  may  be  most  convenient. 


Il6  THE     MODERN     CLOCK. 

When  making  a  new  pallet  fork,  it  is  most  convenient  to 
mark  out  the  lifting  planes  on  the  steel  at  30°  from  the 
tangents,  T,  as  we  then  do  not  have  to  bother  with  the 
escape  wheel  further  than  to  get  its  center  distance  and  the 
degrees  of  arc  the  lifting  planes  are  to  embrace.  The  work- 
man who  is  not  familiar  with  this  rule  is  apt  to  have  his 
ideas  upset  at  first  by  the  angles  of  inclination  toward  the 
center  line  which  the  lifting  planes  will  take  for  different 
center  distances,  as  owing  to  the  fact  that  the  tangents  meet 
on  the  center  line  at  different  angles  for  different  distances, 
the  lifting  planes  assume  different  positions  with  regard  to 
the  center  line  and  he  may  think  that  they  do  not  "look 


06.'P''''T'-^^>P:<> 


Fig.  31. 


right."  They  are  right,  however,  when  drawn  at  30°  to 
their  tangents.  Fig.  31  shows  several  pallets  with  different 
arcs  arranged  in  line  for  purposes  of  comparison,  each  being 
drawn  according  to  the  above  rule,  as  measurements  with  a 
protractor  will  show. 

We  have  now  arrived  at  the  complete  escapement,  having 
finished  our  pallets.  We  have,  however,  nothing  to  hold 
them  in  position ;  they  must  be  rigidly  held  in  position  with 
regard  to  each  other  and  the  escape  wheel,  consequently  we 
will  make  a  yoke  to  connect  them  to  the  pallet  arbor  out  of 
the  same  steel,  giving  it  any  desired  shape  that  will  not  inter- 
fere with  the  working  of  the  clock.  Two  of  the  most  usual 
forms  are  shown  at  Figs.  32  and  33. 


THE     MODERN    CLOCK. 


Fig.  32. 


ii8 


THE     MODERN     CLOCK. 


Fig.  33. 


THE     MODERN     CLOCK.  II9 

Let  us  see  how  this  rule  will  work  in  repairs.  Suppose 
we  have  a  clock  brought  in  with  the  pallet  fork  missing, 
and  that  the  movement  is  one  of  those  in  which  the  pallet 
arbor  is  held  by  adjustable  cocks  which  have  been  misplaced 
or  lost,  so  that  we  don't  know  the  center  distance  of  the 
pallet  arbor  and  escape  wheel.  We  shall  have  to  make  a 
new  part. 

Measure  the  escape  wheel,  getting  its  diameter  carefully, 
take  half  of  this  as  a  radius,  and  mark  out  the  circle  with  a 
fine  needle  point  on  some  copper,  brass  or  sheet  steel,  draw- 
ing the  escapement  as  detailed  in  Figs.  30  and  32.  Then 
measure  carefully  the  angles  made  by  the  tangents  with  the 
center  line ;  take  the  steel  which  is  to  be  used  in  making  the 
pallets  and  fork ;  draw  on  it  a  center  line ;  lay  off  the 
tangents  and  the  lift  lines ;  draw  the  locking  arcs  and  the 
lifting  planes  carefully  from  the  tangents  and  give  the  rest 
of  the  fork  a  symmetrical  shape.  Use  needle  points  to  draw 
with  and  have  your  protractor  large  enough  to  measure 
your  angles  accurately.  Then  drill  or  saw  out  and  file  to 
your  lines,  except  on  the  locking  and  lifting  planes ;  leave 
these  large  enough  to  stand  grinding  or  polishing  after 
hardening.  Harden ;  draw  to  a  straw  color  and  polish  the 
planes.  Your  verge  will  fit  if  it  has  not  warped  in  harden- 
ing. If  this  is  the  case,  soften  the  center,  keeping  the  heat 
away  from  the  pallets,  and  bend  or  twist  the  arms  until 
the  verge  will  fit  the  drawing,  when  laid  on  top  of  it.  In 
grinding  the  pallets  the  fork  should  be  mounted  on  its  arbor 
and  the  latter  held  between  the  centers  of  a  rounding  up 
tool  while  the  grinding  is  done  by  a  lap  in  the  lathe.  This 
insures  that  the  planes  will  be  parallel  to  the  pallet  arbor 
and  hence  square  with  the  escape  wheel  teeth,  so  that  they 
will  not  create  an  end  thrust  on  either  escape  or  pallet 
arbor.  It  is  also  the  quickest,  easiest  and  most  reliable  way 
of  doing  the  job.  When  clocks  come  in  with  the  pallets 
badly  cut ;  soften  the  center  of  the  fork,  place  the  ends  be- 
tween the  jaws  of  a  vise,  squeeze  enough  to  bring  them 


I20 


THE     MODERN     CLOCK. 


Fig.  34.    Drawing  escape  wheel  to  fit  a  tracing  from  a  pallet  fork. 


THE    MODERN    CLOCK.  121 

closer,  mount  in  the  rounding  up  tool  and  lap  off  the  cut 
planes  until  they  are  smooth  and  stand  at  the  proper  angle ; 
then  polish.    This  is  done  quickly. 

Can  we  work  the  rule  backwards?  Suppose  we  get  a 
clock  in  which  we  have  the  pallet  arbor  adjustable  as  before, 
and  we  have  the  pallet  fork  all  in  good  shape,  but  we  have 
lost  the  escape  wheel,  or  it  has  been  butchered  by  somebody 
before  coming  to  us,  so  that  a  new  one  is  required. 

Take  off  the  pallet  fork;  lay  it  on  a  sheet  of  brass  and 
trace  around  it  carefully  with  a  needle  point,  Fig.  34. 
Mark  the  center  carefully  at  the  pallet  arbor  hole  and  meas- 
ure carefully  the  distance  between  the  pallets  and  mark  that 
center.  Draw  a  center  line  cutting  these  centers  and  ex- 
tending beyond.  Now  draw  the  tangent  from  the  beginning 
of  the  entering  pallet  (as  shown  by  the  tracing  on  our 
brass),  to  the  pallet  center;  do  the  same  with  the  exit  pallet. 
Now  take  a  metal  square  and  place  it  on  one  of  the  tangents 
exactly,  with  the  end  at  the  beginning  of  the  entering  pallet ; 
trace  a  line  cutting  the  line  of  centers  and  we  have  the  radius 
of  our  escape  wheel.  Trace  a  circle  from  the  intersection  of 
the  radius  and  the  center  line  and  we  have  the  circumference 
of  our  escape  wheel.  This  circle  should  also  cut  the  inter- 
section of  the  tangent  and  radius  on  the  other  side  if  it  is 
drawn  correctly;  if  it  does  not  do  this  an  error  has  been 
made  in  the  drawing. 

Having  found  the  diameter  and  circumference  of  our 
escape  wheel  it  may  be  sawed  out  and  mounted  for  wheel 
cutting;  or,  if  we  have  no  wheel  cutter  and  must  make 
the  wheel,  we  must  draw  it  on  the  brass  by  hand  with  a  fine 
needle  point  before  proceeding  to  saw  it  out  by  hand,  Fig. 
35.  Say  that  the  wheel  is  to  have  thirty-two  teeth,  which 
is  a  common  number ;  then  360°  -^  32  ^  ii^°  as  the  space 
between  the  points  of  our  teeth.  Take  a  large  protractor, 
one  with  the  degrees  large  enough  to  be  divided  (I  use  a 
ten-inch)  ;  place  its  center  on  the  center  of  our  escape  wheel, 
set  off  ii^°  and  mark  them  on  the  brass  with  the  needle 


122 


THE     MODERN     CLOCK. 


Fig.  35.    Drawing  an  escape  wheel  to  cut.    The  last  drawing  shows  the 
complete  wheel. 


THE    MODERN    CLOCK.  I23 

point,  at  the  edge  of  the  protractor.  Then  take  a  straight 
edge  and  draw  a  radius  from  the  center  to  the  circumfer- 
ence ;  change  the  straight  edge  to  the  other  mark  and  mark 
the  point  where  it  crosses  the  circumference;  set  your 
dividers  accurately  by  this  mark  and  space  off  the  teeth  on 
your  circumference.  If  they  are  set  at  eleven  degrees  and 
fifteen  minutes  they  will  come  out  exactly  at  the  end.  Now 
take  your  protractor  and  with  its  center  at  the  junction  of 
the  radius  and  circumference  set  off  ten  degrees  and  draw 
a  line  past  the  center  of  the  wheel ;  set  off  twenty  degrees 
and  draw  another  line  the  same  way.  From  the  center  of  the 
escape  wheel  draw  two  circles  just  touching  these  lines. 
Outside  of  these  draw  two  circles  defining  the  inner  and 
outer  edges  of  the  rim  of  the  wheel.  With  the  straight  edge 
just  touching  the  inner  circle  draw  in  the  fronts  of  the  teeth ; 
these  will  all  be  set  at  ten  degrees  from  a  radius,  so  that 
only  the  extreme  points  will  touch  the  locking  planes  of 
the  pallets  and  thus  reduce  the  friction  during  the  run.  The 
backs  of  the  teeth  are  marked  out  in  the  same  way  from 
the  twenty-degree  circle.  The  hub  is  made  to  coincide  with 
the  ten-degree  circle;  the  spokes  are  traced  in  and  we  are 
ready  to  begin  sawing  out. 

If  the  workman  has  a  wheel  cutter  the  job  is  much 
simpler.  A  piece  of  brass  is  mounted  on  a  cement  brass 
with  soft  solder,  faced  off,  centered  and  the  pitch  circle, 
inner  and  outer  edges  of  the  rim  and  the  hub  are  traced  with 
the  T-rest  and  graver.  The  extra  metal  is  then  cut  away 
and  a  suitable  index  placed  on  the  spindle  and  locked.  The 
wheel  cutter  is  set  up  with  a  fine  toothed,  smooth  cutting 
saw  on  the  spindle,  horizontal,  with  its  upper  edge  at  the 
line  of  centers  of  the  lathe.  It  is  then  run  out  to  the  cir- 
cumference of  the  wheel,  turned  upwards  ten  degrees  and 
the  wheel  cut  around.  Fig.  36.  This  makes  the  fronts  of  the 
teeth.  Turn  the  saw  ten  degrees  more  and  cut  the  backs 
of  the  teeth.  Then  turn  the  saw  so  that  it  will  reach  from 
the  front  of  one  tooth  to  the  root  of  the  back  of  the  next 


124  "^^^     MODERN     CLOCK. 


Fig.  36.    Making  an  escape  wheel  with  a  saw,  showing  the  successive 

cuts. 


THE    MODERN    CLOCK.  1 25 

one,  without  touching  either  tooth,  and  cut  round  again; 
this  cuts  out  a  triangular  piece  of  waste  metal  between  the 
teeth.  Turn  the  saw  again  so  that  it  reaches  from  the  bot- 
tom of  the  front  of  a  tooth  to  the  top  of  the  back  of  the  next 
one  and  cut  around  again,  thus  removing  another  portion 
of  the  waste  metal,  and  leaving  only  a  small  triangle  be- 
tween the  teeth.  Lower  the  saw  its  own  thickness  and  cut 
around  the  wheel  again,  repeating  the  operation  until  the 
waste  metal  is  all  removed  and  you  have  a  smooth  circular 
rim  between  the  teeth.  Fig.  36. 

Set  the  saw  horizontally  at  the  lathe  center ;  raise  it  one- 
half  the  thickness  of  the  spokes;  set  the  index  pin  of  the 
lathe  head  firmly  at  O ;  feed  in  the  saw  the  thickness  of  the 
wheel  and  make  straight  cuts  across  from  the  circle  of  the 
inner  rim  to  the  circle  marking  the  hub,  but  not  cutting 
either ;  set  the  index  pin  at  30  and  repeat ;  next  lower  your 
saw  and  cut  the  other  side  of  the  spokes  the  same  way. 

Next  you  can  mount  a  lap  in  place  of  the  saw  and  smooth 
the  fronts  and  backs  of  the  teeth  and  if  you  have  a  rather 
thick  disc  the  outer  edge  of  the  rim,  between  the  teeth, 
may  also  be  smoothed. 

If  you  have  a  good  strong  pivot  polisher,  mount  a  tri- 
angular end  mill  in  the  spindle,  lock  the  yoke,  and  cut  the 
arcs  of  circles  of  the  hub  and  rim  from  edge  to  edge  of 
the  spokes,  feeding  carefully  against  the  mill  with  the  hand 
on  the  lathe  pulley. 

Put  on  your  jeweling  tailstock  and  open  the  wheel  to  fit 
the  pinion,  collet,  or  arbor,  if  there  is  no  collet. 

You  now  have  the  wheel  all  done,  except  facing  the  side 
that  was  soldered  to  the  cement  brass  and  trimming  up  the 
corners  of  the  spokes  at  the  rim  and  hub,  and  3^ou  have  got 
it  round,  true  and  correct  in  much  less  time  than  you  could 
have  done  in  any  other  way,  while  an  immense  amount  of 
work  with  the  file  and  eye-glass  has  been  avoided.  It  is 
true  because  it  was  soldered  in  position  at  the  beginning  and 
has  not  been  removed  until  finished. 


126  THK     MODERN     CLOCK 

Sometimes  what  are  known  from  their  appearance  as 
club-shaped  teeth  are  used  in  the  wheels  of  Graham's 
escapements.  Pendulums  receive  their  impulse  from  escape- 
ments made  in  this  manner  partly  from  the  lifting  planes  on 
-the  pallets,  and  partly  from  the  planes  on  the  scape- wheel. 
The  advantage  gained  by  this  method  is,  that  wheels  made 
in  this  way  will  work  with  the  least  possible  drop,  and  con- 
sequently, power  is  saved;  but  the  power  saved  is  thrown 
away  again  in  the  increased  friction  of  the  planes  of  the 
wheel  against  those  of  the  pallets,  which  is  considerably 
more  than  when  plain-pointed  teeth  are  used  on  the  escape 
wheel. 

Clock  pallets  are  usually  made  of  steel,  and  on  the  finer 
classes  of  work  jewels  are  often  set  into  them  to  prevent  the 
oil  from  drying,  after  the  same  fashion  as  jewels  are  placed 
in  steel  pallets  in  a  lever  watch ;  but  it  is  obvious  that  stone 
pallets  made  in  this  way  have  to  be  finished  with  polishers 
held  in  the  hand,  and  that,  except  in  factories,  they  cannot 
he  made  so  perfectly  regular,  especially  that  pallet  that  is 
struck  downwards,  as  the  particular  action  of  a  fine  Graham 
escapement  requires.  When  great  accuracy  is  required,  the 
pallets  are  usually  made  of  separate  pieces,  and  the  acting 
circles  ground  and  polished  on  laps,  running  in  a  lathe. 
This  method  of  constructing  pallets  also  allows  a  means  of 
adjustment  which  in  some  particular  instances  is  very  con- 
venient. 

There  is  also  a  plan  of  making  jeweled  pallets  adjustable, 
which  is  practiced  on  fine  work,  such  as  astronomical  and 
master  clocks.  The  pallet  fork  consists  of  two  pieces  of 
thin,  hard,  sheet  brass,  cut  out  in  the  usual  form  and  two 
mounted  on  one  arbor.  Circular  grooves  are  cut  in  the 
p^des  of  both  plates,  at  the  proper  distance,  and  of  the 
proper  size  t-o  receive  the  jewels  which  are  the  acting  parte 
of  the  pallets.  When  jewels  cannot  be  made  of  the  desired 
size,  pallets  of  steel  are  made,  and  the  jewels  are  then  set 
into  the  steel  Ictrge  enough  for  the  teeth  of  the  wheel  to  act 


THE     MODERN     CLOCK, 


127 


o 


Fig.  37.  Brocot's  visible  escapement,  escaping  over  120*  with  pointed 
teeth.  Dotted  lines  on  pallets  show  where  they  are  cut  to  avoid 
stopping. 


128  THE    MODERN     CLOCK. 

Upon.  The  two  parts  of  the  fork  are  fastened  at  a  given 
distance  apart,  and  the  jewels,  or  pieces  of  steel,  go  in  be- 
tween them,  and,  after  they  have  been  adjusted  to  the  proper 
position,  are  fastened  by  screws  that  pull  the  frames  close 
together  and  press  against  the  edges  of  the  jewels.  Pallets 
made  in  this  manner  have  a  very  elegant  appearance.  An- 
other method  is  to  have  only  one  frame,  and  to  have  it  thick 
enough,  where  the  jewels  have  to  be  set  in,  to  allow  a  groove 
to  be  cut  in  its  side  as  deep  as  the  jewels  (or  the  pieces  of 
steel  that  hold  the  jewels)  are  broad,  and  which  are  held  in 
their  proper  position  by  screws.  This  system  of  jeweling 
pallets  is  frequently  adopted  by  the  makers  of  fine  mantel 
clocks. 

Brocoi's  Visible  Escapement. — Fig.  ^y  represents  a 
system  of  making  and  jeweling  pallets  much  used  by  the 
French  in  their  small  work,  especially  in  visible  escapements. 
The  acting  parts  of  the  pallets  are  simply  cylinders,  gener- 
ally of  colored  stones,  usually  garnets,  one-half  of  each 
cylinder  being  cut  away.  These  cylinders  extend  some  dis- 
tance from  the  front  of  the  pallet  frame,  and  work  into  the 
escape  wheel  the  same  as  the  pallets  of  a  Graham  escape- 
ment— the  round  parts  of  the  pallets  serving  as  impulse 
planes.  The  neck  of  the  brass  pallet  frame  is  cut  up  in  the 
center,  and  the  width  between  the  pallets  is  sometimes  ad- 
justed by  a  screw,  sometimes  by  bending  the  arms. 

Clock  movements  with  this  escapement,  of  a  careful  con- 
struction, will  frequently  come  for  repairs,  accompanied  by 
the  complaint  of  constant  stopping  and  that  no  attempt  at 
closely  regulating  can  succeed  with  them,  although  they 
appear  to  have  no  visible  disturbing  cause.  In  such  cases 
the  depthing  of  the  escapement  is  generally  wrong.  With 
proper  depthing  the  point  of  the  escape  wheel  tooth  should 
drop  on  the  center  or  a  little  beyond  the  center  of  the  pallet 
stone.  If  it  is  set  in  this  way  the  clock  will  stop  when 
wound,  especially  if  it  has  a  strong  spring,   as  the  light 


THE     MODERN    CLOCK. 


129 


Fig.  38.    Brocot's  visible  escapement  escaping  over  90°  with  a  small  lift 
on  the  escape  wheel  teeth. 


130  THE     MODERN     CLOCK. 

pendulum  will  not  then  have  momentum  enough  to  unlock 
it  against  the  full  power  of  the  spring.  If  the  pallets  are  set 
shallow,  in  order  to  avoid  this  difficulty,  then,  the  pendulum 
will  take  too  short  a  swing  and  thus  the  clock  will  have  a 
gaining  rate.  Generally  the  pendulum  ball  cannot  be  made 
enough  heavier  to  correct  the  defect. 

In  these  movements,  in  which  the  length  of  the  pendulum 
does  not  exceed  4  inches,  the  pallet  fork  embraces,  generally 
about  120°,  or  the  one-third  part  of  the  wheel;  it  will  be 
seen  that  unless  there  are  stop  works  on  the  barrel  of  the 
main  spring  no  manner  of  regulating  is  possible  with  these 
conditions,  in  view  of  the  considerable  influence  exercised 
by  the  mainspring  through  the  train  on  the  very  light  pendu- 
lum, and  by  replacing  this  unduly  high  anchor  by  a  lower 
one,  I  have  always  been  able  to  produce  a  very  satisfactory 
rate  with  movements  having  pendulums  of  three  and  a  half 
to  four  inches.  Fig.  38  shows  a  90°  escapement  with  a 
small  lift  on  the  escape  wheel  teeth. 

In  spite  of  its  incontestable  qualities,  the  visible  escape- 
ment possesses  one  inherent  fault.  I  refer  to  the  formation 
of  its  pallets,  the  semi-circular  shape  of  which  renders 
unequal  the  action  of  the  train  in  giving  impulse  to  the 
pendulum  exceeding  50  centimeters  (20  inches),  since  to 
make  it  to  describe  arcs  of  from  one  to  two  degrees  only, 
with  pendulums  of  from  60  centimeters  to  one  meter  in 
length,  it  became  necessary  to  make  the  anchor  arms  ex- 
tremely long,  which  considerably  impeded  the  freedom  of 
action,  especially  when  the  oil  became  thick,  and  this  dis- 
position would,  therefore,  stand  in  direct  contradiction  with 
the  principles  of  modern  horology.  Both  stopping  and 
the  irregularity  of  rate  can  be  obviated  by  changing  the 
semi-circular  form  of  the  pallets  for  one  of  an  inclinea 
plane,  either  by  grinding  a  new  plane  or  turning  the  stones 
in  such  manner  as  to  offer  an  inclined  plane  to  the  action 
of  the  wheel,  analagous  to  that  of  the  Graham  escapement. 


THE     MODERN     CLOCK.  I3I 

See  Fig.  37,  the  dotted  lines  on  the  pallets  showing  the 
portion  to  be  ground  away. 

The  importance  of  this  transformation  will  readily  be 
understood ;  it  suffices  to  give  to  these  planes  a  more  or  less 
large  inclination  in  order  to  obtain  a  greater  regularity  of 
lifting,  and,  at  desire,  a  lifting  arc  more  or  less  considerable 
without  being  compelled  to  modify  the  proportions  of  the 
fork  or  to  exaggerate  the  center  distance  of  wheel  and 
pallet  arbor. 

In  adjusting  an  escapement,  perhaps  it  may  be  advisable 
to  mention  that  moving  the  pallets  closer  together,  or  open- 
ing them  wider,  will  only  adjust  the  drop  on  one  side,  while 
the  other  drop  can  only  be  affected  by  altering  the  distance 
between  the  centers  of  the  pallets  and  scape-wheel.  This  is 
accomplished  in  various  ways.  The  French  method  con- 
sists of  an  eccentric  bush,  riveted  in  the  frame  just  tight 
enough  to  be  turned  by  a  screw-driver.  Another  plan,  com- 
mon in  America,  is  simply  pieces  of  brass  (cocks)  fastened 
on  the  sides  of  the  frames.  The  pivots  of  the  pallet  axis  are 
hung. in  holes  in  these  cocks,  and  an  adjustment  of  great 
accuracy  may  be  quickly  obtained  by  loosening  the  clamping 
screws.  Lock,  drop  and  run  should  be  of  the  same  amount 
on  each  pallet.  However,  we  do  not  approve  of  adjustments 
of  any  kind,  except  in  the  very  highest  class  of  clocks, 
where  they  ai^  always  likely  to  be  under  the  care  of  skillful 
people,  who  understand  how  to  use  the  adjustments  to  obtain 
nicety  of  action  in  the  various  parts. 

In  making  escapements,  lightness  of  all  the  parts  ought 
to  be  an  object  always  in  view  in  the  mind  of  the  workman, 
and  such  materials  should  be  used  as  will  best  serve  that 
purpose.  The  scape-wheel,  and  the  pallets  and  fork,  should 
have  no  more  metal  in  them  than  is  necessary  for  stiffness. 
The  pallet  arbor,  and  also  the  escape-wheel  arbor,  should 
be  left  pretty  thick  when  the  wheel  and  pallets  are  placed 
in  the  center  between  the  plates,  to  prevent  their  springing 
when  giving  impulse  to  the  pendulum.    We  have  often  been 


132  THE     MODERN     CLOCK. 

puzzled  to  find  out  the  necessity  or  the  utihty  of  placing 
them  in  the  center  between  the  plates,  as  they  are  so  gener- 
ally done  in  English  clockwork.  The  escapement  acts  much 
more  firmly  when  it  is  placed  near  one  of  the  plates,  and  it 
is  just  as  easy  to  make  it  in  this  way  as  in  the  other. 

It  is  often  assumed  that  the  friction  of  the  teeth  on  the 
circular  part  of  the  pallets  of  a  dead-beat  escapement  is 
small  in  amount  and  unimportant  in  its  value.  With  re- 
spect to  its  amount,  we  believe  it  is  often  not  far  short  of 
being  equal  to  one-half  of  the  combined  retarding  forces 
presented  to  the  pendulum;  and  with  respect  to  its  being 
unimportant,  this  assumption  is  founded  on  the  supposition 
that  it  is  always  a  uniform  force,  when  it  is  easy  to  show 
that  it  is  not  a  uniform  force.  It  is  very  well  known  that  the 
force  transmitted  in  clock  trains,  from  each  wheel  to  the 
next,  is  very  far  from  being  constant.  Small  defects  in  the 
forms  of  the  teeth  of  the  wheels  and  of  the  leaves  of  the 
pinions,  and  also  in  the  depths  to  which  they  are  set  into 
each  other,  cause  irregularities  in  the  amount  of  power 
transmitted  from  each  wheel  to  the  next ;  and  the  accidental 
combination  of  these  irregularities  in  a  train  of  four  or  five 
wheels,  makes  the  force  transmitted  from  the  first  to  the  last 
exceedingly  variable.  The  wearing  of  the  parts  and  the 
change  in  the  state  of  the  oil,  are  causes  of  further  irregu- 
larities ;  and,  from  these  causes,  it  must  be  admitted  that  the 
propelling  power  of  the  scape-wheel  on  the  pallets  is  of  a 
variable  amount,  and  a  more  important  question  for  consid- 
eration than  it  is  usually  supposed  to  be.  To  avoid  the  con- 
sequences of  this  irregular  pressure  of  the  scape-wheel  on 
the  pallets  being  communicated  to  the  pendulum,  is  a  prob- 
lem that  has  puzzled  skillful  mechanicians  for  many  years ; 
for,  although  we  find  the  Graham  escapement  to  be  pro- 
nounced both  theoretically  and  mechanically  correct,  and 
by  some  authorities  little  short  of  perfection,  we  find  some  of 
these  same  authorities — both  theoretically  and  practically — 
testify  their  dissatisfaction  with  it  by  endeavoring  to  im- 


THE     MODERN     CLOCK. 


33 


prove  on  it.  In  Europe  the  experience  of  generations  and 
the  expenditure  of  small  fortunes,  in  pursuit  of  this  im- 
provement, through  the  agency  of  the  gravity,  and  other 
::orms  of  escapements,  proves  this  fact ;  while  of  late  years, 
in  the  United  States,  much  time  and  money  has  been  spent 
on  the  same  subject,  and  results  have  been  reached  which 
have  raised  questions  that  ten  years  ago  were  little  dreamed 
of  by  those  clockmakers  who  are  generally  engaged  on  the 
highest  class  of  work. 

While  considering  this  class  of  escapements,  we  would 
say  a  few  words  in  regard  to  the  sizes  of  escape  wheels 
generally  used.  Small  wheels  can  now  be  cut  as  accurately 
as  larger  ones  and  there  is  now  no  reason  or  necessity  for 
continuing  the  use  of  a  wheel  of  the  size  Graham  and 
Le  Paute  used,  and  which  has  been  the  size  generally 
adopted  by  most  European  makers  who  use  these  escape- 
ments. The  Germans  and  Swiss  make  wheels  much  smaller 
for  Graham  escapements  than  the  English  makers  do ;  and 
the  American  factories  make  them  smaller  still.  On  the 
continent  of  Europe  the  wheels  of  Le  Paute's  escapement 
are  made  much  larger  than  they  are  made  in  England  and 
in  the  United  States.  No  wheel,  and  more  especially  a 
scape-wheel,  should  be  larger  than  will  just  give  sufficient 
strength  for  the  number  of  teeth  it  has  to  contain,  in  pro- 
portion to  the  amount  of  work  that  it  has  to  perform.  The 
amount  of  work  a  scape-wheel  has  to  perform  in  giving  mo- 
tion to  the  pendulum  is  of  the  lightest  description,  and  not 
more  than  one-tenth  of  what  it  is  popularly  supposed  to 
be,  which  is  shown  by  its  variation  under  slight  increase  of 
friction ;  therefore  we  do  not  consider  that  we  take  extreme 
ground  in  recommending  wheels  for  these  escapements  to  be 
made  nearly  half  the  size  their  originators  made  them,  and 
the  pallets  drawn  off  in  proportion  to  the  reduced  size  of 
the  wheel.  It  is  plain  that  by  reducing  the  size  of  the  wheel 
its  inertia  will  be  reduced.  When  the  teeth  begin  to  act 
on  the  inclined  planes  of  the  pallets,  the  wheel  will  be  set  in 


134 


THE    MODERN    CLOCK. 


motion  with  greater  ease,  as  it  has  a  shorter  leverage,  and 
the  amount  of  the  dead  friction  of  the  scape-wheel  teeth  on 
the  inclined  planes  and  circular  part  of  the  pallets  will  also 
be  proportionately  reduced  by  making  the  wheel  smaller. 
Factory  experience  and  examination  of  a  large  number  of 
clocks  in  repair  shops  have  also  shown  that  smaller  and 
thicker  escape  .wheels  will  wear  much  longer  than  larger 
and  thinner  ones,  as  all  the  wear  is  at  the  points  of  the 
teeth  and  this  is  the  portion  to  be  protected. 


CHAPTER  IX. 

LE  PAUTE's   pin   wheel  ESCAPEMENT. 

Probably  in  no  other  escapement,  except  the  lever,  has 
there  been  so  many  modifications  as  in  the  pin  wheel ;  this 
is  so  to  such  an  extent  that  it  will  be  found  by  the  student 
that  nearly  every  escapement  of  this  kind  which  he  will 
examine  will  differ  from  its  fellows  if  it  has  been  made  by 
a  different  maker.  They  will  be  found  to  vary  in  the  lengths 
of  the  pallet  arms  from  three-fourths  to  one  and  a  half  times 
the  diameter  of  the  escape  wheel;  some  of  them  will  have 
the  longer  arm  of  the  pallets  outside  and  some  inside;  some 
will  have  the  lift  for  both  pallets  laid  out  on  one  side  of  the 
perpendicular  P,  Fig.  39,  while  others  will  have  the  lift 
divided,  with  the  perpendicular  in  the  center.  Very  old 
escapements  have  the  pallet  center  directly  over  the  escape 
wheel  center,  while  the  pallet  arms  work  at  an  angle  of  45°, 
while  others  have  them  with  the  pallet  center  planted  on  a 
perpendicular,  tangent  to  the  pitch  line  of  the  escape  wheel. 
Some  have  the  circular  rest  or  locking  faces  of  the  pallets 
rounded  slightly  to  hold  the  oil  in  position  while  others  have 
them  flat  and  still  others  have  them  made  of  hard  stone,  pol- 
ished. More  than  half  have  the  pins  in  the  escape  wheel  cut 
away  for  one-half  of  their  diameters,  leaving  the  bottoms 
Vound,  as  shown  in  Fig.  39,  while  others  use  a  wider  pin  and 
trim  away  the  bottoms  also,  as  in  Fig.  40,  leaving  the  lifting 
surface  on  the  pins  not  more  than  one-fourth  the  arc  of  the 
circle.  This  is  especially  true  of  the  larger  escapements 
used  in  tower  clocks,  though  they  are  also  found  in  regu- 
lators. 

In  view  of  the  wide  variation  in  practice,  therefore,  we 
have  endeavored  to  present  in  Fig.  39  a  conservative  state- 

135 


36 


TJIE    MODERN    CI.OCK. 


ment  of  the  general  practice  as  found  in  existing  clocks.  We 
say  existing,  because  very  few  of  these  escapements  are 
made  now — none  at  all  in  America — and  those  in  use  are 


Fig.  39.    Pin  Wheel  Escapement. 


generally  in  imported  regulators,  which  have  come  from 
Switzerland  or  Germany.  The  Waterbury  Clock  Co.  at 
one  time  made  this  escapement  for  its  regulators  and  the 


THE    MODERN    CLOCK. 


137 


Seth  Thomas  Clock  Company  made  a  number  of  its  early 
tower  clocks  with  it,  but  both  have  discontinued  it  for  some 
years,  and  it  is  safe  to  say  that  any  movement  coming  into 


Fig.  40.    Pin  Wheel  With  Flattened  Teeth. 


the  watchmaker's  hands  which  has  this  escapement  is  im- 
ported; or  if  American,  it  is  out  of  the  market. 

Le  Paute  claimed  as  an  advantage  the  fact  that  the  im- 
pact of  the  escape  wheel  teeth  is  downward  on  both  pallets, 
whereas  in  the  gravity  and  recoil  escapements  one  blow  is 
struck  upwards  and  the  other  downwards.    He  claimed  that 


138  THE    MODERN    CLOCK. 

by  this  means  a  better  action  was  secured  after  the  pivot 
holes  began  to  wear,  as  there  was  less  lost  motion  with  both 
blows  in  the  same  direction  and  any  shake  would  not  affect 
the  amount  of  impulse  given  to  the  pendulum.  The  differ- 
ence is  more  theoretical  than  practical,  however,  and  the 
escapement  possesses  one  serious  fault,  which  is  that  the 
pins  forming!  the  escape  wheel  teeth  conduct  the  oil  away 
from  thC;  palliets,  so  that  the  clock  changes  its  rate  in  from 
eight  months  H;o  one  year  after  being  oiled  and  cleaned.  The 
most  effective  means  of  counteracting  this  is  to  round  the 
locking  planes  of  the  pallets  slightly,  so  that  the  oil  will  be 
held  on  them  by  capillary  attraction.  Another  method  is 
to  turn  the  pins  so  that  they  are  thicker  in  diameter  at  the 
point  of  contact  with  the  pallets,  but  this  is  seldom  tried. 
The  best  plan  is  to  keep  the  pallets  as  close  as  they  can  be 
to  the  face  of  the  wheel  without  touching. 

To  Draw  the  Escapement. — In  laying  out  this  escape- 
ment the  first  thing  to  consider  is  the  arc  of  swing  of  the 
pendulum,  because  one-half  of  the  lift  is  on  the  pin  and 
consequently  one-half  the  lift  must  equal  one-half  the  diam- 
eter of  the  pin,  as  shown  in  Fig.  39.  If  the  pendulum  swings 
four  degrees,  then  the  diameter  of  each  pin  must  equal  four 
degrees  of  the  pallet  movement.  This  establishes  the  size  of 
our  pin ;  it  is  measured  from  the  pallet  staff  hole.  There  are 
30  of  these  pins  for  a  second's  pendulum,  and  unless  it  is  a 
very  large  escapement  the  pins  cannot  be  made  less  in  di- 
ameter than  one-fourth  the  distance  between  the  pins,  or 
they  will  be  too  weak  and  will  spring;  consequently 
360-4-30=12°  and  i2°-^4=3°,  so  that  three  degrees  of 
the  pitch  line  of  the  escape  wheel  equals  the  swing  of  the 
pallet  fork.  This  establishes  the  relation  as  to  size  between 
the  escape  wheel  and  the  opening,  or  swing  of  the  pallet 
fork.  Draw  a  perpendicular,  P,  from  the  pallet  center  and 
on  one  side  of  it  lay  out  the  lift  lines  L,  L;  draw  a  line  at 
right  angles  to  the  perpendicular  and  where  it  crosses  the 


THE    MODERN    CLOCK. 


39 


inner  lift  line  draw  a  circle  touching  the  outer  lift  line.  The 
diameter  of  this  circle  equals  three  degrees  of  the  circum- 
ference of  the  wheel,  on  its  pitch  line,  and  .this  multiplied  by 
120  gives  360°  or  the  pitch  circumference  of  the  escape 
wheel.  Dividing  the  sum  so  found  by  3. 141 5  gives  the  di- 
ameter of  the  escape  wheel  and  half  of  this  is  the  radius. 
After  finding  the  radius  draw  the  pitch  circle  and  set  out 
the  other  twenty-nine  teeth  spaced  twelve  degrees  apart,  and 
drawn  in  half  circles  as  shown  in  Fig.  39. 

Now  to  get  the  thickness  of  the  pallet  arms.  When  the 
pin  shown  in  action  in  Fig.  39  has  just  cleared  the  lower 
edge  of  the  inner  pallet,  the  succeeding  pin  should  fall  safely 
on  the  upper  corner  of  the  outer  pallet;  consequently  the 
thickness  of  these  two  arms,  the  pin  between  them,  and  the 
drop  (clearance  between  the  pin  and  the  lower  edge  of  the 
upper  pallet)  should  just  equal  the  distance  between  two 
pins,  from  center  to  center,  or  12°  of  the  escape  wheel. 
With  the  first  or  inner  lift  line  as  a  starting  point,  draw  the 
lower  arcs  of  the  pallets  and  draw  the  upper  or  locking 
planes  from  the  perpendicular  and  the  outer  lift  line.  Then 
draw  the  lifting  planes  of  the  pallets  by  connecting  the  ends 
of  these  arcs.  The  enlarged  view  above  the  escape  wheel 
in  Fig.  39  will  show  how  this  is  done  more  clearly  than  the 
main  drawing. 

It  is  best  to  make  the  pallet  fork  of  steel,  in  two  pieces, 
screwed  to  a  collet  on  the  pallet  arbor,  as  the  inner  arm  must 
be  bent,  or  offset,  so  that  it  will  clear  the  pins  of  the  escape 
wheel,  and  the  pallets  should  lie  in  the  same  plane,  as  close 
to  the  wheel  as  is  possible  without  touching  it.  The  pallets 
are  hardened. 

In  tower  clocks  the  escapement  is  so  large  that  a  pin 
having  a  diameter  of  three  degrees  of  the  escape  wheel  gives 
a  half  pin  of  greater  strength  than  is  necessary  for  the 
work  to  be  done  and  such  pins  are  cut  away  on  the  bottom, 
as  in  Fig.  40.  In  making  the  wheel  it  should  be  drilled  in 
the  lathe  with  the  proper  index  to  divide  the  wheel  and  the 


140  THE    MODERN    CLOCK. 

pins  riveted  in;  then  the  pins  are  cut  with  a  wheel  cutter 
as  if  they  were  teeth  of  a  wheel.  Pins  should  be  of  hard 
brass. 

Care  should  be  used  in  handling  clocks  with  this  escape- 
ment while  the  pendulum  is  connected  with  the  pallet  fork, 
as,  if  the  motion  of  the  fork  should  be  reversed  while  a  pin 
was  on  one  of  the  lifting  planes,  it  would  bend  or  break  the 
pin. 


CHAPTER  X. 

THE  RECOIL  OR  ANCHOR  ESCAPEMENT. 

This  escapement,  always  a  favorite  with  clockmakers, 
has  had  a  long  and  interesting  history  and  development. 
Because  it  started  with  a  suddenly  achieved  reputation,  and 
because  it  is  adapted  to  obtain  fair  results  with  the  cheapest 
and  consequently  most  unfavorable  working  conditions,  it 
has  won  its  way  into  almost  universal  use  in  the  cheaper 
classes  of  clock  work;  that  is  to  say,  it  is  used  in  about 
ninety  per  cent  of  the  pendulum  clocks  which  are  manu- 
factured to-day. 

It  achieved  a  sudden  reputation  at  its  birth,  because  it 
was  designed  to  replace  the  old  verge,  which,  with  its  ninety 
degree  pallets  close  to  the  arbor,  and  working  into  the 
crown  wheel,  required  a  very  large  swing  of  the  pendulum. 
This  necessitated  a  light  ball,  a  short  rod,  required  a  great 
force  to  drive  it,  and  made  it  impossible  to  do  away  with 
the  circular  error,  while  leaving  the  clock  sensitive  to  vari- 
ations in  power.  The  recoil  escapement  was  therefore  the 
first  considerable  advance  in  accuracy,  as  its  use  involved 
a  longer  and  heavier  pendulum,  shorter  arcs  of  vibration 
and  less  motive  power  than  was  practicable  with  the  verge ; 
and  as  the  pendulum  was  less  controlled  by  the  escapement, 
it  was  less  influenced  by  variations  of  power. 

In  the  early  escapements  the  entrance  pallet  was  convex 
and  the  exit  pallet  concave.  Escapements  of  this  description 
may  still  be  met  with  among  the  antiquities  that  occasionally 
drift  into  the  repair  shop.  Later  on  both  pallets  were  made 
straight,  as  shown  in  Fig.  41.  It  will  be  seen  by  studying 
the  direction  of  the  forces  that  the  effect  is  to  wear  off  the 

141 


142 


THE    MODERN    CLOCK. 


points  of  the  teeth  very  rapidly,  and  for  this  reason  the 
pallets  were  both  made  convex  (See  Fig.  42),  so  as  to  bring 
the  rubbing  action  of  the  recoil  more  on  the  sides  of  the 


Fig.  41.    Recoil  Escapement  with  Straight  Lifting  Planes. 


teeth  and  do  away  to  a  large  extent  with  the  butting  on  the 
points  which  destroyed  them  so  rapidly. 

The  rather  empirical  methods  of  laying  out  the  recoil 
escapement,  which  have  gained  general  circulation  in  works 
on  horology,  have  had  much  to  do  with  bad  depthings  of 


THE    MODERN    CLOCK.  I43 

.this  escapement  and  the  consequent  undue  wear  of  the 
escape  wheel  teeth  and  great  variation  in  time  keeping  of 
the  movements  in  which  such  faulty  depthings  occur,  par- 
ticularly in  eight-day  movements  with  short  and  light  pen- 
dulums. The  escapement  will  invariably  drive  the  clock 
faster  for  an  increase  of  power  and  slower  for  a  decrease ; 
an  unduly  great  depthing  will  greatly  increase  the  arc  of 
vibration  of  the  pendulum,  as  the  train  exerts  pressure  on 
the  pendulum  for  a  longer  period  during  the  vibration ;  the 
consequence  is  that  instead  of  the  pendulum  being  as  highly 
detached  as  possible,  we  have  the  opposite  state  of  affairs 
and  a  combination  of  a  strong  spring,  light  pendulum  and 
excessive  depthing  will  easily  make  a  variation  of  five  min- 
utes a  week  in  an  eight-day  clock. 

The  generally  accepted  method  of  laying  out  this  escape- 
ment is  shown  in  Figs.  41  and  42,  as  follows :  "Draw  a 
circle  representing  the  escape  wheel ;  multiply  the  radius  of 
the  escape  wheel  by  1.4  and  set  off  this  as  the  center  dis- 
tance between  the  pallet  and  escape  wheel  centers.  From 
the  pallet  staff  center  describe  a  circle  with  a  radius  equal  to 
half  the  distance  between  escape  wheel  and  pallet  centers. 
Set  off  on  each  side  of  the  center  line  one-half  the  number  of 
teeth  to  be  embraced  by  the  pallets  and  from  the  points  of 
the  outside  teeth  draw  lines  tangent  to  the  circle  described 
from  the  pallet  center.  These  lines  would  then  form  the 
faces  of  the  pallets  if  they  w^ere  left  flat." 

We  wonder  how  much  information  this  description  and 
the  drawing  conveys  to  the  average  reader.  How  long 
should  the  pallets  be?  What  is  the  drop?  How  much  will 
the  escape  wheel  recoil  w^ith  such  a  depthing?  What  arc 
will  the  pallets  give  the  pendulum  ?  Why  should  the  center 
distance  always  be  the  same  (seven  tenths  of  the  diameter 
of  the  wheel)  whether  the  escapement  embraces  eight,  or  ten, 
or  six  teeth  ?  As  a  matter  of  fact  it  should  not  be  the  same. 
We  could  ask  a  few  more  questions  as  to  other  details  of 
this  formula,  but  it  will  be  seen  that  such  a  description  is 


144 


THE    MODERN    CLOCK. 


practically  useless  to  all  but  those  who  are  already  so  skilled 
that  they  do  not  need  it. 


Fig.  42.    Recoil  Escapement  with  Curved  Lifting  Planes. 


Let  us  analyze  these  drawings.  A  little  study  of  Figs. 
41,  42  and  43  will  show  that  there  is  really  only  one  point  of 
difference  between  them  and  Fig.  32,  which  shows  the  ele- 


THE    MODERN    CLOCK. 


H5 


ments  of  the  Graham,  or  dead  beat.  The  sole  difference  is 
in  the  fact  that  there  are  no  separate  locking  planes  in  the 
recoil,  the  locking  and  run  taking  place  on  an  extension  of 
the  lifting  planes.  Otherwise  we  have  the  same  elements 
in  our  problem  and  it  may  therefore  be  laid  out  and  handled 


V      -L 


Fig.  43.    Drawing  the  Lock  Lift  and  Recoil  of  the  Usual  Form. 


in  the  same  manner;  indeed,  if  we  were  to  set  off  on  Fig. 
32,  the  amount  of  angular  motion  of  the  pallet  fork  which 
is  taken  up  by  the  run  of  the  escape  wheel  teeth  on  the 
locking  planes,  by  drawing  dotted  lines  above  the  tangents, 
T,  we  should  then  have  measured  all  the  angles  necessary  to 
intelligently  set  out  the  recoil  escapement.  We  should  have 
the  lock  at  the  tangent,  T,  the  lift  and  the  run  (or  recoil) 


146 


THE    MODERN    CLUCK. 


being  defined  by  the  lines  on  either  side  of  it,  and  the  length 
of  our  running  and  lifting  planes  would  be  found  for  the 
entering  pallet  by  drawing  a  straight  line  between  the  points 
of  the  two  acting  teeth  of  the  escape  wheel  and  noting 
where  this  line  cut  the  lines  of  recoil  and  lift.  A  similar 
line  traced  at  right  angles  to  this  would  in  the  same  way 


Fig.  43.     Show  in 


lie  Usual- Position  in  Cheap  Clocks  and  the  Verge 
Wire. 


define  the  limits  of  run  and  lift  on  the  exit  pallet.  It  will 
therefore  be  seen  that  our  center  distances  for  any  desired 
angle  of  escapement  may  be  found  in  the  same  way  (Fig. 
28),  for  either  escapement,  and  thus  the  method  of  making 
the  pallets  for  the  ordinary  American  clock,  Fig.  43,  be- 
comes readily  intelligible.  The  sole  object  of  curving  the 
pallets,  as  explained  previously,  was  to  decrease  the  butting 
effect  of  the  run  on  the  points  of  the  teeth.     This  is  ac- 


THE    MODERN    CLOCK. 


147 


complished  in  Fig.  43  by  straight  planes  on  the  pallets  and 
straight  sides  to  the  teeth  with  20°  teeth  on  the  escape 
wheel;  merely  inclining  the  plane  of  the  entering  pallet 
about  six  degrees  toward  the  escape  wheel  center,  thus  serv- 


Fig.  44.    Recoil  with  Curved  Planes. 


ing  all  purposes, 'while  the  gain  in  the  cost  of  manufacture 
by  using  straight  instead  of  curved  pallets  and  wheel  teeth 
is  very  great. 

One  factory  in  the  United  States  is  turning  out  2,000,000 
annually  of  two  movements,  or  about  1,000,000  of  each 
movement;  there  are  four  other  larger  factories  and  several 


148  TJIE    MODERN    CLOCK. 

with  a  less  product;  so  it  will  readily  be  seen  that  any  de- 
crease in  cost,  however  small  it  may  be  on  a  single  move- 
ment, will  run  up  enormously  on  a  year's  output.  Suppose 
the  factory  mentioned  were  enabled  to  save  only  one-eighth 
r>f  a  cent  on  one  of  its  million  movements  manufactured  last 
year,  this  would  amount  to  $1,250  per  year,  a  little  over 
$100  per  month.  Thus  it  will  be  seen  that  close  figuring  on 
costs  of  production  is  a  necessity. 


Fig.  46.    Drum  Escapement. 

Fig.  44  shows  the  method  of  drawing  the  escapement 
according  to  the  common  sense  deductions  given  above.  As 
the  methods  of  laying  out  the  angle  of  escapement,  lock,  lift, 
and  run,  were  given  in  detail  in  Figs.  28  to  32,  they  need  not 
be  repeated  here. 

Fig.  46  shows  the  escapement  frequently  used  in  French 
"drum''  clocks  and  hence  called  the  "Drum"'  escapement. 
These  are  clocks  fitted  to  go  in  any  hole  of  the  diameter  of 
the  dial  and  hence  they  have  very  short,  light  pendulums. 
An  attempt  is  made  to  gain  control  over  the  pendulum  by 


THE    MODERN    CLOCK.  I49 

decreasing  the  arc  of  escapement  to  not  more  than  two  and 
sometimes  to  only  one  tooth.  This  gives  an  impulse  to  the 
pendulum  only  on  one-half  of  the  vibrations,  the  escape 
wheel  teeth  resting  and  running  on  the  long  circular  locking 
pallet  during  alternate  swings  of  the  pendulum.  The  idea 
is  that  the  friction  of  the  long  lock  will  tend  to  reduce  the' 
effect  of  the  extra  force  of  the  mainspring  when  the  clock 
is  freshly  wound.  Such  clocks  often  stop  when  the  clock 
is  nearly  run  down,  from  deficiency  of  power,  and  stop 
when  wound,  because  the  friction  of  the  escape  wheel  teeth 
on  the  locking  plane  is  such  as  to  destroy  the  momentum 
of  the  light  pendulum.  All  that  can  be  done  in  such  cases 
is  to  alter  the  locking  planes  as  shown  by  the  dotted  lines, 
so  that  the  "drum"  becomes  virtually  a  recoil  escapement 
of  two  teeth.   ' 


CHAPTER  XI. 

THE  DENNISON    OR   GRAVITY   ESCAPEMENT. 

The  distinguishing  feature  of  this  escapement  lies  in  the 
fact  that  it  aims  to  drive  the  pendrlum  by  appl}dng  to  it  a 
falling  weight  at  each  excursion  on  each  side.  As  the  weight 
is  lifted  by  the  train  and  applied  to  the  pendulum  on  its  re- 
turn stroke  and  there  is  no  other  connection,  it  follows  that 
the  pendulum  is  more  highly  detached  than  in  any  other 
form  of  pendulum  escapement.  This  should  make  it  a  bet- 
ter time-keeper,  as  the  application  of  the  weight  should  give 
a  constant  impulse  and  hence  errors  and  variations  in  the 
power  which  drives  the  train  may  be  neglected. 

On  tower  clocks  this  is  undoubtedly  true,  as  these  clocks 
are  interfered  with  by  every  wind  that  blows  against  the 
hands,  so  that  a  detached  pendulum  enables  a  surplus  of 
power  to  be  applied  to  the  train  to  meet  all  emergencies. 
With  a  watchmaker's  regulator,  however,  the  case  is  dif- 
ferent. Here  every  effort  is  made  to  favor  the  clock,  vibra- 
tions, variations  of  temperature,  variations  of  power,  dirt, 
dust,  wind  pressure  and  irregularities  of  the  mechanism  are 
all  carefully  excluded  and  the  consequence  is  that  the  spe- 
cial advantages  of  the  gravity  escapement  are  not  apparent, 
for  the  reason  that  there  are  practically  no  variations  for 
the  escapement  to  take  care  of.  Added  to  this  we  must  con- 
sider that  the  double  three-legged  form,  which  is  the  usual 
one,  is  practically  an  escape  wheel  of  but  six  teeth,  so  that 
another  wfleel  and  pinion  must  be  added  to  the  train  and  this, 
with  the  added  complications  of  the  fan  and  the  heavier  driv- 
ing weight  required,  counterbalance  its  advantages  and  bring 
it  back  to  an  equality  of  performance  with  the  simpler  mech- 
anism of  the  well  made  and  properly  adjusted  dead  beat  es- 

150 


THE    MODERN    CLOCK.  I^I 

capement.  Theoretically  it  should  work  far  better  than  the 
dead  beat,  as  it  is  more  detached ;  but  theory  is  always  modi- 
fied by  working  conditions  and  if  the  variations  are  lacking 
there  is  no  special  advantage  in  constructing  a  mechanism 
to  take  care  of  them.  This  is  the  reason  why  so  many 
watchmakers  have  constructed  for  themselves  a  regulator 
with  this  escapement,  used  in  the  making  all  the  care  and 
skill  of  which  they  were  capable  and  then  been  disappointed 
to  find  that  it  gave  no  better  results  with  the  same  pendulum 
than  the  dead  beat  it  was  to  replace.  They  had  eliminated 
all  the  conditions  under  which  the  detached  escapement 
would  have  shown  superiority. 

Although  the  gravity  escapement  will  not  give  a  superior 
performance  under  the  most  favorable  conditions  for  time- 
keeping, it  is  distinctly  superior  when  these  conditions  are 
unfavorable  and  therefore  fully  merits  its  high  place  in  the 
estimation  of  the  horological  fraternity.  We  have  instanced 
its  value  in  tower  clock  work;  it  has  another  advantage  in 
running  cheap  and  poorly  made  (home  made)  regulators 
with  rough  and  poor  trains  ;  therefore,  it  is  a  favorite  escape- 
ment  with  watchmakers  who  build  their  ow^n  regulators 
while  they  are  still  working  at  the  bench,  before  entering 
into  business  for  themselves.  As  the  price. of  a  first-class 
clock  for  this  purpose  is  about  $300  and  the  cheapest  that  is 
at  all  reliable  is  about  $75,  it  will  be  seen  that  the  tempta- 
tion to  build  a  clock  is  very  strong  and  many  of  them  are 
built  annually. 

Regulators  with  the  gravity  escapement  are  built  by  the 
Seth  Thomas  Clock  Co.,  the  Howard,  and  one  or  two  others 
in  this  country,  but  they  are  furnished  simply  to  supply  the 
demand  and  sales  are  never  pushed  for  the  reasons  given 
previously.  Clocks  with  this  escapement  are  quite  common 
in  England  and  many  of  them  have  found  their  way  to 
America.  It  is  one  of  the  anomalies  of  trade  that  our  clock- 
makers  are  supplying  Europe  with  cheap  clocks,  while  we 
are  importing  practically  all  the  high-priced  clocks  sold  in 


153 


THE    MODERN    CLOCK. 


Fig.  47. 


THE    MODERN    CLOCK.  I53 

the  United  States  and  among  them  are  a  few  having  the 
three-legged  and  four-legged  gravity  escapements,  therefore 
the  chances  are  that  when  a  repairer  finds  such  a  clock  it  is 
likely  to  be  either  of  English  origin  or  homemade,  unless  it 
be  a  German  regulator. 

Figs.  47  and  48  show  plans  and  side  views  of  the  three- 
legged  escapement.  Fig.  48  also  shows  an  enlarged  view  of 
the  escape  wheel,  showing  how  the  three-leaved  pinion  be- 
tween the  tw^o  escape  wheels,  is  made  where  it  is  worked 
out  of  the  solid.  A,  B  and  C  and  a,  b  and  c  show  the  escape 
wheel  which  is  made  up  of  two  three-armed  wheels,  one  on 
each  side  of  a  three-leaved  pinion  marked  D^  and  D^  in  the 
enlarged  view  of  Fig.  48.  The  pallets  in  this  escapement 
consist  of  the  two  arms  of  metal  suspended  from  points  op- 
posite the  point  of  bending  of  the  pendulum  spring  and  the 
lifting  planes  are  found  on  the  ends  of  the  center  arms  in 
these  pallets,  which  press  against  the  three  leaves  of  the 
pinion,  while  the  impulse  pins  e^  and  e-.  Fig.  47  and  48  act 
directly  upon  the  pendulum  in  place  of  the  verge  wire.  The 
pallets  act  between  the  wheels  in  the  same  plane  as  each 
other.  The  lifting  pins  or  pinion  leaves  act  on  the  lifting 
planes  after  the  line  of  centers  when  the  long  teeth  or  legs 
of  the  escape  wheels  have  been  released  from  the  stops,  F 
and  G,  Figs.  47  and  48,  which  are  placed  one  on  each  side 
of  the  pallets  and  act  alternately  on  the  wheels.  These  pal- 
lets are  pivoted  one  on  each  side  of  the  bending  point  of  the 
suspension  spring.  To  lay  out  the  escapement,  draw  a  cir- 
cle representing  the  escape  wheel  diameter,  then  draw  the 
line  of  centers  and  set  off  on  the  diameter  of  the  escape 
wheel  from  each  side  of  the  line  of  centers  60°  of  its  cir- 
cumference, thus  marking  the  positions  for  the  pallet  stops 
120°  apart.  Draw  radii  from  the  center  of  the  escape  wheel 
to  these  positions  and  draw  tangents  from  the  ends  of  these 
radii  toward  the  center  line.  The  point  where  these  meet 
will  be  the  bending  point  of  the  pendulum  spring. 


154 


THE    MODERN    CLOCK. 


Fig.  48. 


THE    MODERN    CLOCK.  I55 

This  is  clearly  shown  at  H,  Fig.  47.  The  points  of  sus- 
pension for  the  pallets  are  planted  on  the  line  of  these  tan- 
gents and  a  little  be!ow  the  point  H,  where  the  tangents  meet 
on  the  line  of  centers.  This  is  done  to  avoid  the  mechanical 
difficulty  of  having  the  studs  for  the  two  pallets  occupy  the 
same  place  at  the  same  time.  The  arms  of  the  pallets  below 
the  stops  may  be  of  any  length,  but  they  are  generally  con- 
structed of  the  same  angle  as  the  upper  arms  and  will  be 
all  right  if  drawn  parallel  to  these  upper  arms.  They  are  in 
some  instances  continued  further  down,  but  this  is  largely 
a  matter  of  taste  and  the  lower  portion  of  the  escapement  is 
generally  drawn  so  as  to  be  symmetrical. 

The  impulse  of  the  pendulum  is  given  by  having  pins  prO" 
jecting  from  the  pallet  arms  and  bearing  upon  the  pendulum 
rod,  which  pins  may  be  of  brass,  steel  or  ivory.  In  the 
heavier  escapements  they  are  made  of  ivory  in  order  to  avoid 
any  chatter  from  contact  with  the  pendulum  rod  of  a  heavy 
pendulum.  These  pallets  should  be  as  light  as  it  is  possible 
to  make  them  without  having  them  chatter  under  the  im- 
pact of  the  escape  wheel  arms  on  the  stops.  They  have  only 
to  counteract  the  force  of  the  pendulum  spring  and  the  re- 
sistance of  the  air  and  for  light  pendulums  this  force  is  much 
less  than  is  generally  understood.  Two  ounces  of  impulse 
will  maintain  a  250-pound  pendulum,  but  two  pennyweights 
is  more  than  sufficient  for  a  fifty-pound  pendulum.  The 
reader  can  see  that  in  the  case  of  a  pendulum  weighing  but 
eight  to  fourteen  pounds,  there  w^ill  be  a  still  greater  pro- 
portionate drop,  as  the  spring  itself  is  thinner,  the  rod  is 
thinner,  the  pendulum  ball  oi¥ers  little  resistance  to  the  air 
and  the  consequence  is  that  it  is  difficult  to  get  the  pallet 
arms  light  enough  for  an  ordinary  clock. 

Watchmakers  who  make  this  escapement  for  themselves, 
to  drive  an  eight  to  fourteen  pound  pendulum.,  generally 
make  the  escape  wheel  three  inches  diameter  and  make  the 
escape  wheel  and  pallet  arms  all  from  the  steel  obtained  by 
buying   an   ordinary   carpenter's   saw.     The   lifting  planes 


1^6  THE    MODERN    CLOCK. 

should  not  be  more  than  one-eighth  its  diameter  from  the 
center  of  the  escape  wheel,  as  where  this  is  the  case  the 
circular  motion  of  the  center  pins  will  be  so  great  that  the 
pallet  in  action  will  be  thrown  out  too  rapidly  and  will  chat- 
ter when  striking  the  pendulum  rod.  On  the  other  hand  it 
should  not  be  less  than  one-twelfth  of  the  diameter  of  the 
escape  wheel,  or  the  pendulum  will  not  be  given  sufficiently 
free  swing  and  the  motion  will  be  so  slow  that  while  such  a 
clock  will  work  under  favorable  conditions,  jarring,  shak- 
ing in  wind  storms,  etc.,  will  have  a  tendency  to  make  the 
pendulum  wabble  and  stop  the  clock.  From  what  has  been 
said  above,  it  will  also  be  seen  that  the  necessity  for  slow 
motion  of  the  pallet  arms  unfits  this  escapement  for  use  with 
short  pendulums. 

The  action  of  the  escapement  is  as  follows :  The  pendu- 
lum traveling  to  the  right,  when  it  has  thrown  the  right 
pallet  arm  sufficiently  far,  will  liberate  the  escape  wheel 
tooth  from  the  stop  G  and  the  pinion,  acting  on  the  lifting 
plane,  will  raise  the  pallet  arm,  allowing  the  pendulum  to 
continue  its  course  without  doing  any  further  work  until 
it  has  reached  nearly  its  extreme  point  of  excursion,  when 
the  weight  of  the  pallet  will  be  dropped  upon  the  pendulum 
rod  and  remain  there,  acting  upon  the  pendulum  until  it  has 
passed  the  center  when  the  pallet  arm  will  be  stopped  by  the 
banking  pin  M^ ;  exactly  the  same  procedure  takes  place  on 
the  left  side  of  the  escapement  during  the  swing  of  the  pen- 
dulum to  the  left.  The  beat  pins  M  and  M^  should  be  set 
so  that  the  impulse  pins  e^  and  e^  will  just  touch  the  pen- 
dulum when  the  latter  is  hanging  at  rest  and  the  escapement 
will  then  be  in  beat.  The  stops  should  be  cut  from  sheet 
steel  and  the  locking  faces  of  the  escape  wheel  arms,  stops 
on  the  pallets,  lifting  planes  of  the  pallets  and  the  lifting  pins 
should  all  be  hardened.  In  some  of  the  very  fine  escape- 
ments the  faces  of  the  blocks  are  jeweled.  The  arnis  of  the 
inner  part  of  the  escape  wheel  are  usually  set  at  equal  an- 
gular distances  between  those  of  the  outer,  although  this  is 


THE    MODERN    CLOCK. 


157 


not  absolutely  necessary,  and  the  lifting  pins  are  set  on  radii 
to  the  acting  faces  of  the  arms  of  one  of  the  wheels,  so  as  to 
cross  the  line  of  centers  at  the  distance  from  the  center,  not 
exceeding  one-eighth  of  the  radius  of  the  wheel,  for  the 
reasons  explained  above. 


Fig.  49. 

From  the  comparatively  great  angle  at  which  the  arms  are 
placed,  the  distance  through  which  they  have  to  be  lifted  to 
give  sufficient  impulse  is  less  in  this  escapement  than  in  one 
with  a  larger  number  of  teeth  acting  in  the  same  plane,  as 
the  pallets  would  then  hang  more  nearly  upright.  This  is  a 
great  advantage,  as  the  contact  is  shorter.  The  unlocking  is 
also  easier  for  the  same  reason,  and  from  the  greater  diame- 
ter of  the  wheel  in  proportion  to  other  parts  of  the  escape- 


138  THE    MODERN    CLOCK. 

ment,  the  pressure  on  the  stops  is  considerably  less.  The  two 
wheels  must  be  squared  on  the  arbor,  so  there  will  be  no 
possibility  of  slipping.  The  lifting  pins  D  are  shouldered 
between  them  like  a  three-tooth  lantern  pinion.  In  small 
escapements  the  lifting  pins  are  not  worked  out  of  the  solid 
arbor,  but  are  made  as  hardened  screws  to  connect  the  two 
portions  of  the  wheel.  In  tower  clocks  the  pinion  is  gener- 
ally made  solid  on  the  shaft  J,  Fig.  48.  The  wheel,  A,  B,  C, 
is  made  to  pass  over  the  pinion  D  and  is  fitted  to  a  trian- 
gular seat,  the  size  of  the  triangle  of  the  leaves,  D,  against 
the  collar  on  the  shaft.  The  other  wheel,  a,  b,  c,  is  fitted 
to  the  inside  triangle  of  the  pinion,  so  that  the  leaves,  D, 
form  a  shoulder  against  which  it  fits.  The  pallets,  E  and  E^, 
also  lie  in  one  plane  between  the  wheels,  but  one  stop,  F, 
points  forward  to  receive  the  A,  B,  C,  teeth  and  the  other, 
G,  points  backward  to  receive  the  a,  b,  c  teeth  alternately. 
The  distance  of  the  pendulum  top,  H,  or  cheeks  from  the 
center  of  the  escape  wheel,  J  equals  the  diameter  of  the 
escape  wheel.  The  lifting  pins  should  be  so  placed  that  the 
one  which  is  holding  up  a  pallet  and  the  one  which  is  to  lift 
next  will  be  vertical  over  each  other,  on  the  line  of  centers, 
the  third  pin  being  on  the  level  with  the  center,  and  to  one 
side  of  it,  see  Fig.  48,  enlarged  view. 

The  fly  is  a  very  essential  part  of  this  escapement,  as  the 
angular  motion  of  the  escape  wheel  is  such  that  unless  it 
were  checked  it  would  be  apt  to  rebound  and  unlock;  con- 
sequently, a  large  fly  is  always  a  feature  of  this  escapement 
and  is  mounted  upon  the  scape  wheel  arbor  with  spring  fric- 
tion in  such  a  way  that  the  fly  can  continue  motion  after  the 
scape  wheel  has  been  stopped.  This  is  provided  for  by  a 
spring  pressure,  either  like  the  ordinary  spring  attachment 
of  the  fly  of  striking  trains  of  small  clocks,  or  as  shown  in 
Fig.  49  for  tower  clocks.  This  fly  is  effective  in  propor- 
tion to  its  length  and  hence  a  long  narrow  fly  will  be  better 
than  a  shorter  and  wider  one,  as  the  resistance  of  the  air 


THE    MODERN    CLOCK. 


159 


Fig,  50. 


l6o  THE    MODERN    CLOCK. 

striking  against  the  ends  of  the  fly  is  much  greater  the  fur- 
ther you  get  from  the  center. 

The  pallet  stud  pins  and  the  impulse  pins  should  on  no 
account  be  touched  with  oil  or  other  grease  of  any  kind, 
-but  be  left  dry  whatever  they  are  made  of,  because  the  slight- 
est adhesion  betw^een  the  impulse  pins  and  the  pendulum  rod 
is  fatal  to  the  whole  action  of  the  escapement.  Care  must 
also  be  taken  that  one  pallet  begins  to  lift  simultaneously 
with  the  resting  of  the  other,  neither  before  nor  after. 

The  gravity  escapement  requires  a  heavier  weight  or 
force  to  operate  the  train  than  a  dead  beat  escapement,  be- 
cause it  must  be  strong  enough  to  be  sure  of  lifting  the  pal- 
lets quickly  and  firmly,  and  also  because  the  escape  wheel 
having  but  six  teeth  necessitates  the  use  of  another  wheel 
and  pinion  between  the  escape  and  center  and  consequently 
the  train  is  geared  back  more  than  it  would  be  for  a  dead 
beat  escapement,  with  the  seconds  hand  mounted  on  the  es- 
cape wheel  arbor.  But  with  this  form  of  escapement  the 
superfluous  force  does  not  work  the  pendulum  and  it  does 
no  harm  if  the  train  is  good  enough  not  to  waste  power  in 
getting  over  rough  places  left  in  cutting  the  teeth  of  the 
wheels  or  any  jamming  from  those  which  have  unequal 
widths  or  spaces.  For  this  reason  a  high  numbered  train  is 
better  than  a  low  numbered  one,  as  these  defects  are  greater 
on  the  teeth  of  a  low  numbered  train  and  any  defect  in  such 
cases  will  show  itself. 

In  the  gravity  escapement  the  escape  wheel  must  have  a 
little  run  at  the  pallets  before  it  begins  to  lift  them  and  in 
order  to  do  this  the  banking  pins,  M,  M^,  for  the  pallet  arms 
to  rest  on,  should  hold  them  just  clear  of  the  lifting  pins 
or  leaves  of  the  escape  wheel.  The  escape  wheel  should  be 
as  light  as  possible,  for  every  blow  heard  in  the  machine 
means  a  loss  of  power  and  wear  of  parts.  Of  course,  in  an 
escapement  a  sudden  stop  is  expected,  but  the  light  wheel 
will  reduce  it  to  a  minimum  if  the  fan  is  large  enough.  Par- 
ticular attention  should  therefore  be  given  to  the  length  of 


THE    MODERN    CLOCK. 


i6i 


O 


Fig.  51. 


l62  THE    MODERN    CLOCK. 

this  fan  and  if  the  stop  of  the  escape  wheel  seems  too  ab- 
rupt, the  fan  should  be  lengthened. 

Figs.  50  and  51  show  the  same  escapement  with  a  four- 
legged  wheel  instead  of  the  double  three-legged.  In  this 
case,  where  there  is  but  one  wheel,  the  pallets  must  of  ne- 
cessity work  on  opposite  sides  of  the  wheel  and  hence  they 
are  not  planted  in  the  same  plane  with  each  other,  but  are 
placed  as  close  to  each  side  of  the  wheel  as  is  practicable. 

To  lay  out  this  escapement,  draw  the  circle  of  the  escape 
wheel  as  before,  make  your  line  of  centers  and  mark  off  on 
the  circle  6yy2°  on  each  side  of  the  line  of  centers  and  draw 
radii  to  these  points,  which  will  indicate  the  approximate 
position  of  the  stops.  Tangents  to  these  radii,  meeting  above 
the  wheel  on  the  line  of  centers  will  give  the  theoretical 
point  of  the  suspension.  One  set  of  the  lifting  pins  is 
planted  on  radii  to  the  acting  faces  of  the  teeth  of  the  es- 
cape wheel.  The  opposite  set,  on  the  other  side  of  the  wheel, 
is  placed  midway  between  the  first  set.  This  secures  the 
lifting  at  the  line  of  centers.  The  wheel  turns  45°  at  each 
beat  and  its  arbor  likewise  carries  a  fly. 

In  case  the  locking  is  not  secure,  the  stops  may  be  shifted 
a  little  up  or  down,  care  being  taken  to  keep  them  135° 
apart.  In  this  way  a  draw  may  be  given  to  the  locking  of 
the  scape  wheel  arms  similar  to  the  draw  of  the  pallets  in 
a  detached  lever  escapement  and  thus  any  desired  resistance 
to  unlocking  may  be  secured.  The  stops  in  either  escape- 
ment are  generally  made  of  steel  and  it  is  of  the  utmost, im- 
portance that. the  arms  of  the  escape  wheel  should  leave  them 
without  imparting  the  least  suspension  of  an  impulse. 
Therefore,  the  stops  and  the  ends  of  the  arms  should  be  cut 
aAvay  (backed  off)  to  rather  a  sharp  angle  to  insure  clear- 
ance when  the  arms  are  leaving  the  stops.  It  is  also  of 
equal  importance  that  the  legs  of  the  wheels  should  fall  on 
the  stops  dead  true.  The  fit  of  each  of  the  legs  should  be 
examined  on  both  stops  with  a  powerful  eye  glass,  so  that 
they  should  be  correct  and  also  see  that  when  the  unlock- 
ing takes  pl?ce  the  wheel  is  absolutely  free  to  turn. 


CHAPTER  XII. 

THE    CYLINDER    ESCAPEMENT    AS    APPLIED    TO    CLOCKS. 

We  remarked  in  a  previous  chapter  that  the  Hfting  planes 
were  sometimes  on  the  wheel  and  sometimes  on  the  anchor. 
In  another  chapter  we  pointed  out  clearly  that  the  run  on  the 
locking  surface  of  the  pallets  had  an  important  bearing  on 
the  freedom  of  the  escapement  and  hence  on  the  rate  of  the 
dead  beat  escapement.  In  considering  the  cylinder  escape- 
ment, so  common  in  carriage  clocks,  we  shall  find  t'tiat  the 
lift  is  almost  entirely  on  the  curved  planes  of  the  escape 
wheel,  and  that  the  locking  planes  are  greatly  extended,  so 
that  they  form  the  outer  and  inner  surfaces  of  the  cylinder 
walls.  Thus  \ve  have  here  a  form  of  the  dead  beat  escape- 
ment, which  embraces  but  one  tooth  of  the  escape  wheel 
and  is  adapted  to  operate  a  balance  instead  of  a  pendulum. 
Therefore  the  points  for  us  to  consider  are  as  before,  the 
amount  of  lift,  lock,  drop  and  run,  and  the  shapes  of  our 
escape  wheel  teeth  to  secure  the  least  friction,  as  our  lock- 
ing surfaces  (the  run)  being  so  greatly  extended  this  mat- 
ter becomes  important. 

Action  of  the  Escapement. — Fig.  52  is  a  plan  of  the  cyl- 
inder escapement,  in  which  the  point  of  a  tooth  of  the  escape 
wheel  is  pressing  against  the  outside  of  the  shell  of  the 
cylinder.  As  the  cylinder,  on  which  the  balance  is  mounted, 
is  moved  around  in  the  direction  of  the  arrow,  the  wedge- 
shaped  tooth  of  the  escape  wheel  pushes  into  the  cylinder, 
thereby  giving  it  impulse.  The  tooth  cannot  escape  at  the 
other  side  of  the  cylinder,  for  the  shell  of  the  cylinder  at 
this  point  is  rather  more  than  half  a  circle ;  but  its  point 
locks  against  the  inner  side  of  the  shell  and  runs  there  till 

163 


164 


THE    MODERN    CLOCK. 


the  balance  completes  its  vibration  and  returns,  when  the 
tooth  which  was  inside  the  cylinder  escapes,  giving  an  im- 
pulse as  it  does  so,  and  the  point  of  the  succeeding  tooth 
is  caught  on  the  outside  of  the  shell.  The  teeth  rise  on 
stalks  from  the  body  of  the  escape  wheel,  and  the  cylinder 
is  cut  away  just  below  the  acting  part  of  the  exit  side,  leav- 


Fig.  52.    a,  wheel;  b,  cylinder;  f,  stalk  on  which  teeth  are  mounted. 

ing  for  support  of  the  balance  only  one-fourth  of  a  circle, 
in  order  to  allow  as  much  vibration  as  possible.  This  will 
be  seen  very  plainly  on  examining  Fig.  53,  which  is  an  ele- 
vation of  the  cylinder  to  an  enlarged  scale. 


Proportion  of  the  Escapement.— The  escape  wheel  has 
fifteen  teeth,  formed  to  give  impulse  to  the  cylinder  during 
from  20°  to  40°  of  its  vibration  each  way.  Lower  angles 
are  as  a  rule  used  with  large  than  with  small-sized  escape- 


THE    MODERN    CLOCK. 


165 


rrtents,  but  to  secure  the  best  result  either  extreme  must  be 
avoided.  In  the  escapement  with  very  slight  inclines  to  the 
wheel  teeth,  the  first  part  of  the  tooth  does  no  work,  as  the 
tooth  drops  on  to  the  lip  of  the  cylinder  some  distance  up 
the  plane.  On  the  other  hand,  a  very  steep  tooth  is  almost 
sure  to  set  in  action  as  the  oil  thickens.     The  diameter  of 


Fig.  53. 


the  cylinder,  its  thickness  and  the  length  of  the  wheel  teeth 
are  all  co-related.  The  size  of  the  cylinder  with  relation  to 
the  wheel  also  varies  somewhat  with  the  angle  of  impulse, 
a  very  high  angle  requiring  a  slightly  larger  cylinder  than 
a  low  one.  If  a  cylinder  of  average  thickness  is  desired  for 
an  escapement  with  medium  impulse,  its  external  diameter 
may  be  made  equal  to  the  extreme  diameter  of  the  escape 
wheel  multiplied  by  0.T15 


66 


THE    MODERN    CLOCK. 


Then  to  set  out  the  escapement,  if  a  Hft  of  say  30°  be 
decided  on,  a  circle  on  which  the  points  of  the  teeth  will 
fall  is  drawn  within  one  representing  the  extreme  diameter 
of  the  escape  wheel,  at  a  distance  from  it  equal  to  30''  of 
the  circumference  of  the  cylinder.     Midway  between  these 


\i^'      \      \       < 


V30»  -i 


Fig.  54, 


two  circles  the  cylinder  is  planted  (see  Fig.  54).  If  the 
point  of  one  tooth  is  shown  resting  on  the  cylinder,  a  space 
of  half  a  degree  should  be  allowed  for  freedom  between 
the  opposite  side  of  the  cylinder  and  the  heel  of  the  next 
tooth.  From  the  heel  of  one  tooth  to  the  heel  of  the  next 
equal  24°  of  the  circumference  of  the  wheel,  360-^15=24°, 
and  from  the  point  of  one  tooth  to  the  point  of  the  next 


THE    MODERN    CLOCK.  167 

also  equals  24°  so  that  the  teeth  may  now  be  drawn.  They 
are  extended  within  the  innermost  dotted  circle  to  give  them 
a  little  more  strength,  and  their  tips  are  rounded  a  little, 
having  the  points  of  the  impulse  planes  on  the  inner  or 
basing  circle.  The  backs  of  the  teeth  diverge  from  a  rad- 
ial line  from  12°  to  30°,  in  order  to  give  the  cylinder  clear- 
ance, a  high  angled  tooth  requiring  to  be  cut  back  more 
than. a  low  one.  A  curve  whose  radius  is  about  two-thirds 
that  of  the  wheel  is  suitable  for  rounding  the  impulse  planes 
of  the  teeth.  The  internal  diameter  of  the  cylinder  should 
be  such  as  to  allow  a  little  freedom  for  the  tooth.  The 
rule  in  fitting  cylinders  is  to  have  equal  clearance  inside  and 
outside,  so  as  to  equalize  the  drop.  The  acting  part  of  the 
shell  of  the  cylinder  (where  the  lips  are  placed)  should  be 
a  trifle  less  than  seven-twelfths  of  a  whole  circle,  with  the 
entering  and  exit  lips  which  are  really  the  pallets,  rounded 
as  shown  in  the  enlarged  plan,  Fig.  55,  the  entering  lip  or 
pallet  rounded  both  ways  and  the  exit  pallet  rounded  from 
the  inside  only.  This  rounding  of  the  lips  of  the  cylinder 
adds  a  little  to  the  impulse  beyond  what  would  be  given 
by  the  angle  on  the  wheel  teeth  alone.  The  diameter  of 
the  escape  wheel  is  usually  half  that  of  the  balance,  rather 
under  than  over. 

Size  of  Cylinder  Pivot. — To  establish  the  size  of  the 
pivot  with  relation  to  its  hole  i^  apparently  an  easy  thing  to 
do  correctly,  but  to  an  inexperienced  workman  it  is  not  so. 
The  side  shake  in  cylinder  pivot  holes  should  be  greater 
than  that  for  ordinary  train  holes ;  one-sixth  is  the  amount 
prescribed  by  Saunier ;  the  size  of  the  pivot  relatively  to  the 
cylinder  about  one-eighth  the  diameter  of  the  body  of  the 
cylinder.  It  is  very  necessary  that  this  amount  of  side 
shake  should  be  correctly  recognized ;  if  less  than  the  amount 
stated,  the  escapement,  though  performing  well  while  the 
oil  is  fresh,  fails  to  do  so  when  it  commences  to  thicken. 

When  the  balance  spring  is  at  rest,  the  balance  should 


THE    MODERN    CLOCK. 


69 


have  to  be  moved  an  equal  amount  each  way  before  a  tooth 
escapes.  By  gently  pressing  against  the  fourth  wheel  with 
a  peg  this  may  be  tried.  There  is  generally  a  dot  on  the 
balance  and  three  dots  on  the  plate  to  assist  in  estimating 
the  amount  of  lift.  When  the  balance  spring  is  at  rest,  the 
dot  on  the  balance  should  be  opposite  to  the  center  dot  on 
the  plate.  The  escapement  will  then  be  in  heat,  that  is,  pro- 
vided the  dots  are  properly  placed,  which  should  be  tested. 
Turn  the  balance  from  its  point  of  rest  till  a  tooth  just  drops, 
and  note  the  position  of  the  dot  on  the  balance  with  refer- 
ence to  one  of  the  outer  dots  on  the  plate.  Turn  the  bal- 
ance in  the  opposite  direction  till  a  tooth  drops  again,  and 
if  the  dot  on  the  balance  is  then  in  the  same  position  with 
reference  to  the  other  outer  dot,  the  escapement  will  be  in 
beat.  The  two  outer  dots  should  mark  the  extent  of  the 
lifting,  and  the  dot  on  the  balance  would  then  be  coincident 
with  them  as  the  teeth  dropped  when  tried  in  this  way ;  but 
the  dots  may  be  a  little  too  wide  or  too  close,  and  it  will 
therefore  be  sufficient  if  the  dot  on  the  balance  bears  the 
same  relative  position  to  them  as  just  explained ;  bnt  if  it 
is  found  that  the  lift  is  unequal  from  the  point  of  rest,  the 
balance  spring  collet  must  be  shifted  in  the  direction  of  the 
least  lift  till  the  lift  is  equal.  A  new  mark  should  then  be 
made  on  the  balance  opposite  to  the  central  dot  on  the 
plate. 

When  the  balance  is  at  rest,  the  banking  pin  in  the  balance 
should  be  opposite  to  the  banking  stud  in  the  cock,  so  as  to 
give  equal  vibration  on  both  sides.  This  is  important  for 
the  following  reason.  The  banking  pin  allows  nearly  a 
turn  of  vibration  and  the  shell  of  the  cylinder  is  but  little 
over  half  a  turn,  so  that  as  the  outside  of  the  shell  gets  round 
towards  the  center  of  the  escape  wheel,  the  point  of  a  tooth 
may  escape  and  jam  the  cylinder  unless  the  vibration  is 
pretty  equally  divided.  When  the  banking  is  properly  ad- 
justed, bring  the  balance  round  till  the  banking  pin  is 
against  the   stud;  there   should  then  be  perceptible  shakL' 


170  THE    MODERN    CLOCK. 

between  the  cylinder  and  the  plane  of  the  escape  wheeL  Try 
this  with  the  banking-  pin,  first  against  one  and  then  against 
the  other  side  of  the  stud.  If  there  is  no  shake,  the  wheel 
may  be  freed  by  taking  a  little  off  the  edge  of  the  passage 
of  the  cylinder  where  it  fouls  the  wheel,  by  means  of  a  sap- 
phire file,  or  a  larger  banking  pin  may  be  substituted  at  the 
judgment  of  the  operator.  See  that  the  banking  pin  and 
stud  are  perfectly  dry  and  clean  before  leaving  them :  a 
sticky  banking  often  stops  a  clock  when  nearly  run  down. 
Cylinder  timepieces,  after  going  for  a  few  months,  some- 
times increase  their  vibration  so  much  as  to  persistently 
bank.  To  meet  this  fault  a  weaker  mainspring  may  be 
used,  or  a  larger  balance,  or  a  wheel  with  a  smaller  angle 
of  impulse.  By  far  the  quickest  and  best  way  is  to  very 
slightly  lap  the  wheel  by  holding  a  piece  of  Arkansas  stone 
against  the  teeth,  afterwards  polishing  with  boxwood  and 
red  stuff.  So  little  taken  off  the  wheel  in  this  way  as  to  be 
hardly  perceptible  will  have  great  effect. 

Sometimes  the  escape  wheel  has  too  much  end  shake.  We 
must  notice  in  the  first  place  how  the  teeth  are  acting  in  the 
cylinder  slot.  Suppose,  when  the  escape  wheel  is  resting 
upon  its  bottom  shoulder,  the  cylinder  will  ride  upon  the 
plane  of  the  wheel,  which  will  cause  it  to  kick  or  give  the 
wheel  a  trembling  motion,  then  we  know  that  the  cylinder 
is  too  low  for  the  wheel ;  therefore,  we  have  not  only  to 
lower  the  escape  top  cock  in  order  to  correct  the  end  shake, 
but  we  must  also  drive  the  bottom  cylinder  plug  out  a  little 
in  order  to  raise  the  cylinder  sufficient  to  free  it  from  the 
plane  of  the  wheel.  Now,  if  the  end  shake  of  the  cylinder  is 
correct  previous  to  this,  we  shall  now  either  have  to  raise 
the  cock  or  drive  the  top  plug  in  a  little.  But  suppose  the 
end  shake  of  the  escape  pinion  is  excessive,  and  is,  when  the 
bottom  shoulder  is  resting  on  the  jewel,  a  little  too  low  so 
that  the  bottom  of  the  escape  wheel  runs  foul  of  the  cylinder 
shell ;  in  this  case  we  simply  drive  out  the  steady  pins  from 
the  bottom  escape  wheel  cock  and  file  a  piece  off  the  cock, 


TilE    MODERN    CLOCK.  lyi 

leaving  it  perfectly  flat  when  we  have  enough  ofi.  We  then 
insert  the  steady  pins  again,  screw  it  down,  and  if  the  end 
shake  is  right,  the  escapement  is  mostly  free  and  right  also. 

Now  let  us  consider  the  frictions ;  there  is  the  resistance 
of  the  pivots,  which  depends  on  their  radius,  on  the  weight 
of  the  balance,  the  balance  spring,  the  collet,  and  the  weight 
of  the  cylinder;  these  are  called  locking  frictions.  Then 
there  are  those  of  the  planes,  of  the  teeth  of  the  wheel,  of  the 
lips  of  the  cylinder.  It  is  on  these  that  the  change  and  de- 
struction of  the  cylinder  are  produced.  To  prevent  this 
destruction,  it  is  necessary  to  render  the  working  parts 
of  the  cylinder  very  hard  and  well  polished,  as  well  as  the 
teeth  of  the  escape  wheel. 

The  oil  introduced  in  the  cylinder  is  also  a  cause  as  in  the 
dead  beat.  It  may  thicken;  the  dust  proceeding  from  the 
impact  of  the  escapement  forms  with  the  oil  an  amalgam 
which  wears  the  cylinder.  The  firmness  and  constancy  of 
the  cylinder  depend  on  the  preservation  and  fluidity  of  the 
oil. 

Then  there  are  the  accidental  frictions ;  the  too  close 
opening  of  the  cylinder,  the  play  of  the  balance  and  of  the 
wheel,  with  the  thickening  of  the  oil,  changes  the  arc  of 
vibration  a  good  deal;  the  teeth  of  the  wheel  may  not  be 
sufficiently  hollowed,  so  that  the  cylinder  can  revolve  in  the 
remaining  space,  for  the  oil  with  the  dust  forms  a  thickness 
which  also  changes  the  vibration.  The  drop  should  not  be 
too  great,  for  it  is  increased  by  the  thickening  of  the  oil 
and  impedes  the  vibration. 

Examination  of  Clocks. — In  this  particular  escape- 
ment, when  used  for  larger  timepieces  than  watches,  it  is 
astonishing  the  variety  of  methods  which  are  employed,  yet 
the  same  results  are  expected.  In  examining  such  clocks 
we  will  first  notice  that  the  chariot,  cock,  etc.,  are  so  placed, 
many  of  them,  that  the  last  wheel  in  the  train  is  a  crown 
wheel,  hence  it  is  made  to  work  at  90°  with  the  escape  wheel 


I'Ji  THK    MODEIIN    CLOCK. 

pinion  which  is  set  at  right  angles  with  the  crown  wheel 
pinion,  and,  as  a  matter  of  course,  the  cylinder  is  also  set 
the  same  way.  Now,  this  arrangement  needs  especial  care, 
for  it  is  quite  natural  that  when  the  entire  friction  of  the 
cylinder  is  only  on  the  bottom  part  of  the  bottom  pivot,  the 
clock  is  sure  to  go  faster  than  when  the  whole  length  of 
both  pivots  are  more  in  contact  with  their  jewel  holes,  w^hich 
is  always  the  case  when  the  cylinder  is  parallel  with  all  the 
pinions,  instead  of  standing  upon  one  pivot  only.  Now,  al- 
though there  must  of  necessity  be  a  very  great  difference  in 
timing  the  clock  in  the  two  different  positions,  yet  we  find 
no  difference  in  the  strength  of  mainspring  or  any  part  of 
the  train,  which  is  a  mistake,  for  the  result  is  simply  this: 
the  clock  will  gain  time  for  the  first  few  days  after  wind- 
ing, and  will  then  gradually  go  slower  and  slower  until  the 
mainspring  is  entirely  exhausted.  It  is  not  very  difficult  to 
ascertain  why  it  goes  so  fast  after  winding,  for  then  the 
whole  tension  of  the  spring  is  on,  and  as  there  is  not  suffi- 
cient friction  on  the  point  of  one  pivot  to  counteract  this, 
the  banking  pin  is  almost  sure  to  knock,  and  will  continue  to 
knock  for  the  first  few  days  until  a  part  of  the  spring's 
pressure  is  exhausted.  Now,  in  this  case  the  knocking  of 
the  banking  pin  alone  would  cause  the  clock  to  gain  time, 
even  if  the  extra  tension  of  the  mainspring  did  not  assist  it 
to  do  so.  Hence,  on  the  whole,  the  result  is  anything  but 
satisfactory,  for  such  a  clock  can  never  be  properly  brought 
to  time. 

Having  said  this  much  about  the  fault  (which  is  entirely 
through  the  want  of  a  little  forethought  with  the  manu- 
facturer), I  will  give  as  good  a  remedy  as  I  can  suggest 
to  give  the  reader  an  idea  of  how  these  faults  may  be  put  to 
right,  if  he  is  willing  to  spend  the  time  upon  them.  In  the 
first  place  take  out  the  cylinder  and  make  the  bottom  pivot 
oerfectly  flat  instead  of  leaving  it  with  a  round  end,  as  they 
are  mostly  left,  which  only  allows  just  one  part  of  the  pivot 
to  be  in  contact  with  the  endstone.     By  leaving  this  pivot 


THE    MODERN    CLOCK.  I73 

flat  on  the  bottom,  there  is  more  surface  in  contact ;  hence, 
in  a  sense,  more  friction. 

In  some  cases  the  whole  pivot  left  flat  would  not  be 
sufficient  to  retard  the  mainspring's  force;  then  we  must 
resort  to  other  methods  to  effect  a  cure. 

Well,  our  next  method  in  order  to  try  and  get  the  clock 
to  be  a  uniform  timekeeper,  is  to  change  the  mainspring  for 
one  well  finished  and  not  quite  so  strong  as  the  original 
one.  Perhaps  some  will  say  "why  not  do  this  before  we  go 
to  the  trouble  of  flattening  the  bottom  pivot?"  Just  this; 
when  a  pivot  •  is  working  only  upon  the  bottom  it  is  best 
to  have  a  flat  surface  to  work  upon,  as  the  balance  is  then 
oscillated  with  more  uniformity,  even  when  the  mainspring 
is  not  exactly  uniform  in  its  pressure;  therefore  we  do  no 
harrur-but  good^by  making  the  bottom  pivot  flat,  and  this 
alone  will  sometimes  be  sufficient  to  cure  the  fault  of  the 
banking  knocking  if  nothing  else. 

To  my  mind,  when  such  strong  mainsprings  are  used  as 
we  generally  see  in  this  class  of  timepiece,  neither  of  the 
jewel  holes  or  pivots  should  be  so  small  as  they  usually  are. 
Fancy  such  small  pivots  as  are  mostly  seen  upon  the  escape 
wheel  pinion  being  driven  by  such  a  strong  mainspring. 
If  we  allow  the  clock  to  run  down  while  the  escape  wheel 
is  in  place,  we  are  very  liable  to  find  one  or  both  pivots 
broken  off  before  it  gets  run  down.  I  think  all  such  pivots 
ought  to  be  sufficiently  strong  to  stand  the  pressure  of  the 
mainspring  through  the  train  of  wheels  without  coming  to 
grief.  But  there  is  another  reason  why  these  pivots  are 
liable  to  get  broken  off  while  letting  the  train  run  down ;  that 
is,  the  badly  pitched  depth  we  often  find  in  the  crown  wheel 
and  escape  wheel  pinion.  We  frequently  find  too  much 
end  shake  to  the'  crown  wheel  which,  while  resting  one 
shoulder  of  the  arbor  against  the  plate  puts  the  depth  too 
deep,  and  on  the  other  shoulder  the  depth  is  too  shallow. 
l^QW,  when  the  train  is  running  rapidly  this  crown  wheel  is 
jumping  about  in  the  escape  wheel  pinion,  so  that  the  rough- 


174  THE    MODERN    CLOCK. 

ness  of  the  running  all  helps  to  break  off  the  escape  wheel 
pivots.  The  best  way  to  correct  this  depth  is  to  notice  how 
the  screws  fit  in  the  cylinder  plate — for  these  screws  have 
to  act  as  steady  pins  as  well.  If  the  holes  where  the  screws 
go  through  are  at  all  large,  we  then  notice  which  would  be 
the  most  convenient  side  to  screw  it  securely  in  order  to  put 
a  collet  upon  the  shoulder  of  the  crown  wheel  so  that  the 
depth  will  be  right  by  making  the  end  shake  right  with  only 
fixing  a  collet  to  one  shoulder.  This  depth,  when  correct, 
will  also  cause  a  more  uniform  pressure  upon  the  escape- 
ment, and  help  to  make  the  clock  keep  better  time.  We  are 
supposing  that  this  crown  wheel  is  perfectly  true,  or  it  is  not 
much  use  trying  to  correct  the  depth  as  mentioned  above, 
for  even  if  the  end  shake  be  ever  so  exact  and  the  wheel 
teeth  are  out  of  true,  we  shall  never  get  the  depth  to  act  as 
it  ought,  neither  can  the  clock  be  depended  upon  for  keep- 
ing going,  regardless  of  keeping  time.  When  this  crown 
wheel  is  out  of  true  it  is  best  to  rivet  it  true,  not  do  as  I 
h;ive  seen  it  done,  placed  in  the  lathe  and  topped  true,  and 
then  the  teeth  rounded  up  by  hand.  This  n]ethod  simply 
means  a  faulty  depth  after  all,  for  in  topping  the  teeth,  those 
teeth  which  require  the  most  topping  will,  when  they  are 
finished,  be  shorter  from  the  top  to  the  base  than  those 
v;hich  do  not  get  topped  so  much;  therefore,  some  of  the 
teeth  are  longer  than  the  others,  while  the  shorter  ones  are 
thicker ;  for  when  the  wheel  was  originally  cut  the  teeth  were 
all  cut  alike.  These  remarks  will  apply  to  several  kinds  of 
wheels;  for  whenever  a  wheel  is  topped  to  put  it  true,  we 
may  depend  w^e  are  making  a  very  faulty  wheel  of  it  unless 
we  have  a  proper  wheel  cutting  machine. 

The  crown  wheel  must  not  be  too  thick  because  we  will 
find  the  tooth  to  act  with  the  inner  edge,  and  what  is  left 
outside  only  endangers  touching  the  pinion  leaf  which  is 
next  to  come  into  action.  Make  sure  the  escape  pinion  is 
not  too  large,  whicji  sometimes  happens.  If  it  is,  it  must 
be  reduced  in  size,  or  better,  put  in  a  new  one.    The  crown 


THE    MODERN    CLOCK. 


175 


wheel  holes  must  fit  nicely  and  the  end  shake  be  well  ad- 
justed. Do  not  spare  any  trouble  in  making  this  depth  as 
perfect  as  you  are  able,  as  most  stoppages  happen  through 
the  faults  in  this  place.  It  would  be  advisable,  when  sure 
the  depth  is  correct,  to  drill  two  steady  pin  holes  through 
the  escapement  plateau  into  the  edge  of  the  plates.  When 
steady  pins  are  inserted  this  will  always  ensure  the  depth 
being  right  when  put  together. 

In  some  of  these  clocks  it  is  not  only  the  crown  wheel, 
but  frequently  the  escape  wheel  has  too  much  end  shake. 
The  former,  as  I  have  said,  can  be  corrected  by  making  a 
small  collet  that  will  just  fit  over  pivot,  fasten  it  on 
friction  tight,  place  the  wheel  in  the  lathe  and  turn 
the  collet  down  until  it  is  the  same  size  as  the  other  part  of 
the  arbor,  then  run  off  the  end  to  the  exact  place  for  the  end 
shake  to  be  right.  If  it  is  properly  done  and  a  steel  collet  is 
used,  it  will  not  be  detected  that  a  collet  has  been  put  on. 
Now,  when  the  escape  wheel  end  shake  is  wrong  we  have  to 
proceed  differently  under  different  circumstances  for  we 
must  notice  in  the  first  place  how  the  teeth  are  acting  in 
the  cylinder  slot. 

See  that  the  cylinder  and  wheel  are  perfectly  upright. 
Suppose,  when  the  escape  wheel  is  resting  upon  its  bottom 
shoulder,  the  cylinder  will  ride  upon  the  plane  of  the  wheel, 
which  will  cause  it  to  kick  or  give  the  wheel  a. trembling 
motion,  then  we  know  that  the  cylinder  is  too  low  for  the 
wheel ;  therefore,  we  have  not  only  to  lower  the  escape  top 
cock  in  order  to  correct  the  end  shake,  but  we  must  also 
drive  the  bottom  cylinder  plug  out  a  little  in  order  to  raise 
the  cylinder  sufficient  to  free  it  from  the  plane  of  the  wheel. 
Now,  if  the  end  shake  of  the  cylinder  is  correct  previous  to 
this,  we  shall  either  have  to  raise  the  cock  or  drive  the  top 
plug  in  a  little.  But  suppose  the  end  shake  of  the  escape 
pinion  is  excessive,  and  is,  when  the  bottom  shoulder  is 
resting  on  the  jewel,  a  little  too  low  so  that  the  bottom  of 
the  escape  wheel  runs  foul  of  the  cylinder  shell ;  in  this  case 


176  THE    MODERN    CLOCK. 

we  simply  drive  out  the  steady  pins  from  bottom  escape 
wheel  cock  and  file  a  piece  off  the  cock,  leaving  it  perfectly 
flat  when  we  have  got  enough  off.  We  then  insert  the 
steady  pins  again,  screw  it. down,  and,  if  the  end  shake  is 
right,  the  escapement  is  mostly  free  and  right  also.  It  some- 
times happens  that  the  wheel  is  free  of  neither  the  top  nor 
bottom  plug,  but  should  this  be  the  case,  suflicient  clearance 
may  be  obtained  by  deepening  the  opening  with  a  steel  pol- 
isher and  oilstone  dust  or  with  a  sapphire  file.  A  cylinder 
with  too  high  an  opening  is  bad,  for  the  oil  is  drawn  away 
from  the  teeth  by  the  escape  wheel. 

If  a  cylinder  pivot  is  bent,  it  may  very  readily  be  straight- 
ened by  placing  a  bushing  of  a  proper  size  over  it. 

These  clocks  are  very  good  for  the  novice  to  exercise  his 
skill  in  order  to  thoroughly  understand  the  workings  of  the 
horizontal  escapement.  He  is  better  able  to  see  how  the 
different  parts  act  with  each  other  than  he  is  in  the  small 
watch.  When  the  escape  is  correct  he  will  find  that  the 
plane  of  the  escape  wheel  will  work  just  in  the  center  of 
the  small  slot  in  the  cylinder. 

If  he  will  notice  how  the  teeth  stand  in  the  cylinder  when 
the  banking  pin  is  held  firmly  upon  the  fixed  banking  pin, 
it  will  give  him  an  idea  of  how  this  should  be.  At  one  side 
the  lip  of  the  cylinder  is  just  about  to  touch  the  inside  of  the 
escape  tooth,  but  the  banking  pin  just  prevents  it  from  doing 
so,  while  on  the  other  side  the  cylinder  goes  round  just 
far  enough  to  let  the  point  of  the  next  tooth  just  get  on  the 
edge  of  the  slot,  but  it  cannot  get  in  owing  to  the  interven- 
tion of  the  banking  pin.  If  this  is  allowed  to  get  in  the  slot 
just  here,  we  then  have  what  is  called  "a  locking,"  which 
is,  in  reality,  an  overturned  banking.  If  the  other  side  is  so 
that  the  banking  pin  does  not  stop  it  soon  enough,  the  edge 
of  the  slot  knocks  upon  the  inside  of  the  teeth  and  causes  a 
trembling  of  the  escape  wheel,  and  the  clock  left  in  this 
form  will  never  keep  very  good  time.  We  may  easily 
remedy  this  by  taking  off  the  hair  spring  collet;  holding  the 


THE    MODERN    CEOCK. 


77 


cylinder  firmly  in  the  plyers,  and  with  the  left  hand  turn 
the  balance  a  little  outwards;  this  will  bring  the  banking 
pins  in  contact  before  the  cylinder  touches  the  inside  of  the 
wheel  teeth,  and  all  is  right,  providing  we  are  careful  in 
not  doing  it  too  much ;  if  so,  we  shall  find  the  banking 
knock — a  fault  which  is  quite  as  bad,  if  not  worse,  than  the 
one  we  are  trying  to  remedy.  Those  particulars  are  the 
most  important  of  anything  in  connection  with  the  cylinder 
escapement.  Yet,  as  this  kind  of  clock  is  now  being  made 
up  at  such  a  low  price,  these  seem^ing  little  items  aie  fre- 
quently overlooked  ;  hence,  when  they  get  into  the  hands 
of  the  inexperienced,  there  is  often  more  trouble  with  them 


Fig.  56. 

than  there  need  be  if  they  knew  where  to  look  for  some  of 
the  faults  which  I  have  been  endeavoring  to  bring  to  light, 
There  are  several  other  things  in  connection  with  this  par- 
ticular clock,  but  we  will  not  comment  further  just  now, 
but  take  them  up  when  we  are  considering  the  trains,  etc. 

In  the  meantime  we  will  resume  our  study  of  the  cylinder 
escapement  with  particular  reference  to  badly  worn  or  other- 
wise ill  fitting  escape  wheels,  as  m.any  times,  the  other  points 
being  right,  the  wheel  and  cylinder  may  be  such  as  to  give 
either  too  great  or  too  small  a  balance  vibration. 

A  poor  motion  can  also  be  due  to  a  rough  or  a  badly  pol- 
ished cylinder,  but  such  a  cylinder  wc  rarely  find.  That 
with  a  wrong  shape  of  the  C3dinder  lips  the  motion  is  not 
much  lessened  can  be  seen  in  quite  ordinary  movements 
where  the  quality  is  certainly  not  of  the  best  neither  are 
the  lips  correctly  formed,  nevertheless  they  have  rather  an 


178  THE    MODERN    CLOCK. 

excessive  motion.  To  cover  up  these  defects  in  such  move- 
ments the  cylinder  wheel  teeth  are  purposely  given  the  shape 
as  shown  at  B  in  Fig.  56,  and  to  give  sufficient  power  a 
strong  mainspring  is  inserted. 
'  With  an  excessive  balance  vibration  we  can  usually  con- 
clude that  it  is  an  intentional  deception  on  the  part  of  the 
manufacturer,  while  a  poor  motion  can  generally  be  ascribed 
to  careless  methods  in  making.  The  continued  efforts  in 
making  improvements  to  quicken  and  cheapen  manufactur- 
ing processes  very  frequently  result  in  the  introduction  of 
defects  which  are  only  found  by  the  experienced  and  practi- 
cal watchmaker 

As  to  the  causes  which  induce  excessive  balance  vibra- 
tions? As  this  defect  is  generally  found  in  the  cheaper 
grades  of  cylinder  escapements,  having  usually  rather  small, 
heavy,  and  often  clumsy  balances,  those  which  have  balances 
whose  weight  is  probably  less  than  they  ought  to  be,  need 
not  here  be  further  considered,  and  it  only  remains  for  us 
to  look  to  the  cylinder  or  the  escape  wheel  for  the  causes 
which  produce  these  excessive  vibrations.  It  will  be  found 
that  the  cylinder  is  smaller  in  diameter  than  usually  em- 
ployed in  such  a  size  of  clock ;  the  escape  wheel  is  naturally 
also  smaller,  and  its  teeth  generally  resemble  B,  Fig.  56, 
while  A  shows  the  correct  shape  of  a  tooth  for  a  wheel  of 
that  diameter. 

In  using  small  cylinders  we  can  give  the  escape  wheel 
teeth  a  somewhcit  greater  angle  of  inclination  than  gener- 
ally used,  but  thnt  tlic  proper  amount  of  incline  is  exceeded 
is  proved  by  the  fact  that  the  balance  vibrates  more  than 
two-thirds  of  a  turn,  it  can  also  be  readily  seen  that  with  a 
tooth  like  B  a  greater  impulse  must  be  imparted  than  one 
with  an  easy  curve  like  A,  and  the  impulse  is  still  further 
increased  as  the  working  width  of  the  tooth  B  (the  lift)  is 
greater,  indicated  by  line  h,  w^iile  the  same  line  in  a  correct 
width  of  tooth,  as  shown  at  a,  is  considerably  shorter. 


THE    MODERN    CLOCK. 


179 


In  addition  to  what  has  been  said  of  these  escapements,  w^ 
also  find  them  provided  with  very  strong  mainsprings  to 
give  the  necessary  power  to  a  tooth  hke  B  with  its  steeply 
inclined  lifting  face  or  impulse  angle. 

To  decrease  the  great  amplitude  of  ^he  balance  vibrations 
many  watchmakers  simply  replace  the  strong  mainspring 
with  a  weaker  one.  But  this  proceedure  is  not  advantageous 
as  the  power  of  the  escape  wheel  tooth  is  insufficient  to 
start  the  balance  going  and  this  is  due  to  two  causes.  First, 
the  great  angle  of  the  escape  wheel  tooth,  and  secondly,  the 
inertia  of  the  balance.  It  is  only  by  violently  shaking  such 
a  clock  that,  we  are  enabled  to  start  it  going.    And  the 


Fig.  57. 


Fig.  58. 


owner  soon  becomes  dissatisfied  from  its  frequent  stoppage 
due  to  setting  of  the  hands  and  other  causes  so  that  he  will 
be  often  obliged  to  shake  it  until  it  starts  going  once  more. 
For  properly  correcting  these  defects  the  best  method  to 
pursue  is  to  replace  the  cylinder  wheel  with  another  one, 
whose  teeth  are  of  the  shape  as  shown  at  Fig.  55  and  with- 
out question  a  good  workman  will  always  replace  the 
escape  wheel  if  the  clock  is  of  fair  quality.  But  if  a  low 
grade  one,  we  would  hardly  be  justified  in  going  to  the  ex- 
pense of  putting  in  new  wheels,  as  the  low  prices  for  which 
these  clocks  are  sold  preclude  such  an  alteration.  As  we 
must  improve  the  wheel  some  way  to  get  a  fair  escapement 
action  we  can  place  it  in  a  lathe  and  while  turning,  hold 


l8o  THE    MODERN    CLOCK. 

an  oil  stone  slip  against  it,  we  can  remove  the  point  S,  Fig. 
56.  After  removing-  the  point  the  tooth  will  now  have  the 
form  as  shown  at  tooth  C,  Fig.  57.  We  now  take  a  thin 
and  rather  broad  watch  mainspring,  bending  a  part  straight 
and  holding  it  in  the  line  /  /,  and  revolving  the  wheel  in  the 
direction  as  shown  b}^  the  arrow,  its  action  being  indicated 
by  figures  i  to  8;  beginning  at  the  point  of  the  tooth  at  i, 
at  2  it  comes  in  contact  with  the  whole  of  the  lifting  face, 
and  from  3  to  8  only  on  the  projecting  corner  which  was  left 
by  the  oil  stone  slip  in  removing  the  heel  of  the  tooth.  In 
this  way  all  the  teeth  are  acted  upon  until  the  corner  is  en- 
tirely removed.  Of  course  oil  stone  dust  and  oil  is  first 
used  upon  the  spring  for  grinding,  after  which  the  teeth  are 
polished  with  diamantine.  Care  must  be  observed  in  using 
the  spring  so  as  not  to  get  the  end  /  too  far  into  the  tooth 
circle,  as  it  would  catch  on  the  heel  of  the  preceding  tooth. 

After  the  foregoing  operation  has  been  completed  any 
feather  edge  remaining  on  the  points  of  the  teeth  must  be 
removed  with  a  sapphire  file  and  polished ;  we  will  now  have 
a  tooth  as  indicated  by  D,  Fig.  57.  This  shape  of  tooth  can 
hardly  be  said  to  be  theoretically  correct,  nevertheless  it 
is  a  close  approximation  of  the  proper  form  of  tooth,  which 
is  shown  by  the  dotted  lines,  and  will  then  perform  its  func- 
tions much  better  than  in  its  original  condition.. 

Fig.  58  also  shows  how  the  spring  must  be  moved  from 
side  to  side — indicated  by  dotted  lines — so  that  the  lifting 
face  will  have  a  gentle  curve  instead  of  being  flat ;  R  repre- 
sents the  tooth. 

After  the  wheel  has  been  finished,  as  described,  and  again 
placed  in  the  clock,  it  will  be  found  that  the  balance  makes 
only  two-thirds  of  a  turn,  and  as  a  result  the  movement  can 
be  easier  brought  to  time  and  closely  regulated. 

In  the  above  I  have  described  the  cause  of  excessive  bal- 
ance vibration,  the  method  by  which  it  can  be  corrected,  and 
in  what  follows  I  shall  endeavor  to  make  clear  the  reasons 
for  a  diminished  balance  vibration  or  poor  motion.     It  has 


THE    MODERN    CLOCK.  l8l 

been  probably  the  experience  of  most  watchmakers  to 
repair  small  cylinders  of  a  low  grade,  having  a  poor  motion 
or  no  motion  at  all,  and  it  would  hardly  be  profitable  to 
expend  much  time  in  repairing  them.  But  considerable 
time  is  often  wasted  in  improving  the  motion  by  polishing 
pivots  and  escape  wheel  teeth,  possibly  replacing  the  cap 
jewels,  or  even  the  hole  jewels,  increasing  the  escapement 
depth  or  making  it  shallower,  examining  the  cylinder  and 
finding  nothing  defective,  and  as  a  last  effort  putting  in  a 
stronger  mainspring.  But  all  in  vain,  the  balance  seems 
tired  and  with  a  slight  pressure  upon  an  arm  of  the  center 
wheel  it  stops  entirely. 


Fig.  59. 

In  this  case,  as  in  a  former  one,  in  fact,  it  is  necessary 
at  all  times  to  carefully  examine  the  cylinder  wheel.  j\Iy 
reason  for  not  considering  the  cylinder  itself  so  much  as  the 
wheel  is  that  the  makers  of  them  have  made  a  considerable 
advance  in  their  methods  of  manufacture,  so  we  find  the 
cylinders  fairly  well  made  and  generally  of  the  correct  size. 
Even  if  the  cylinder  is  incorrectly  sized,  either  too  large  oi 
small,  it  does  not  necessarilv  follow  that  the  watch  would 
have  a  bad  motion,  as  I  have  frequently  had  old  movements 
where  the  cylinder  was  incorrectly  proportioned  and  yet  the 
motion  was  often  a  good,  satisfactory  one.  Generally 
speaking,  the  cylinder  escapement  is  one  which  admits  of  the 
worst  possible  constructive  proportions  and  treatment,  as 
we  have  often  examined  such  clocks  when  left  for  repairs, 


l82  THE    MODERN    CLOCK. 

that,  notwithstanding  their  being  full  of  dirt,  worn  cylinder, 
broken  jewel  holes,  etc.,  they  have  been  running  until  one 
of  the  cylinder  pivots  has  been  completely  worn  away. 

It  only  remains  to  look  for  the  source  of  the  trouble  in  the 
escape  wheel.  If  we  examine  the  wheel  teeth  carefully,  we 
shall  find  them  resembling  those  in  Fig.  59,  the  dotted  lines 
representing  the  correct  shape  of  the  teeth  for  a  wheel  of 
that  diameter. 

Why  do  we  find  wheels  having  such  defective  teeth  ?  This 
is  probably  due  to  their  rapid  manufacture,  as  they  very 
likely  had  the  correct  shape  when  first  cut,  but  by  careless 
grinding  and  polishing  they  were  gfiven  improper  forms, 
careless  treatment  being  very  evident  at  tooth  F,  which  we 
find  on  examination  has  a  feather  edge  at  the  point  as  well 
as  at  the  heel  of  the  tooth.  If  we  grind  these  edges  of  the 
tooth  with  a  ruby  file,  by  placing  it  in  the  position  as  indi- 
cated by  dotted  lines  h  and  /i^,  and  afterwards  polishing  the 
tooth  point,  we  will  find  that  the  balance  makes  a  better 
vibration.  A  wheel,  having  teeth  like  E,  can  still  be  used, 
but  the  balance  will  have  a  very  poor  motion,  due  to  the  fact 
that  the  impulse  angle  of  the  wheel  tooth  is  too  small ;  the 
impulse  faces  of  the  teeth  having  so  small  an  angle,  are  near- 
ly incapable  of  any  action.  With  a  tooth  like  G,  if  we 
should  remove  its  bent  point  at  the  dotted  line  d,  then  th^ 
tooth  would  be  too  short,  and  as  the  inclination  of  the  im- 
pulse face  is  incapable  to  produce  a  proper  action,  a  new 
wheel  must  be  used,  having  teeth  as  shown  at  Fig.  55. 

The  reasons  why  a  tooth,  having  the  shape  as  shown  at 
F  and  G  (Fig.  59),  will  cause  a  bad  action  of  the  escapement 
and  also  why  in  such  cases  with  a  greater  force  acting  on 
the  wheel,  causes  a  stopping  of  the  clock,  I  will  endeavor 
to  explain  with  the  aid  of  the  illustration  Fig.  60.  Here  we 
clearly  see  the  curved  points  of  the-  teeth  resting  against  the 
outer  and  inner  walls  of  the  cylinder  while  the  escapement  is 
in  action. 


THE    MODERN    CLOCK. 


183 


Teeth  H  and  H^  represent  the  defective  tooth,  while  K 
and  K^  shows  a  correctly  formed  tooth  for  a  wheel  of  the 
same  size,  the  correct  depth  and  positions  where  the  tooth 
strikes  the  inner  and  outer  walls  of  the  cylinder.  It  will  be 
readily  seen  that  the  position  of  the  tooth  point  upon  the 
cylinder  (at  c)  is  most  favorable  in  reducing  the  resistance 
to  the  least  possible  amount.  But  in  the  case  of  the  teeth  H 
and  H^  the  condition  is  entirely  different.  We  find  that  it 
v/as  necessary  to  set  the  escapement  very  deeply  in  order 
that  it  could  perform  its  functions  at  all,  and,  as  a  conse- 


Fig 


quence,  we  have  a  false  proportion ;  the  effects  being  con- 
siderably increased  by  the  worst  possible  position  of  the 
teeth  H  and  H^,  where  they  touch  the  cylinder.  While  the 
cylinder  c  is  turning  in  the  direction  shown  by  the  arrows 
i  i^j  the  tooth  does  not  affect  the  cylinder  to  any  extent ;  but 
during  the  reverse  movement  of  the  cylinder,  in  the  direction 
of  0  0^,  an  excessive  amount  of  engaging  friction  must  take 
place.  A  close  inspection  of  the  drawing  will  enable  us  to 
see  that  there  is  a  great  tendency  of  the  cylinder  to  drag 
the  tooth  along  with  it  during  each  of  these  motions.  It  is 
evident  that  in  such  a  case  the  friction  will  eventually  be- 
come so  great  as  to  lock  the  escapement,  and  if  greater 
pressure  is  applied  by  any  means  to  teeth  H  and  H^,  it  is 
easily  seen  that  this  eifect  will  take  place  much. more  rapidly. 
Replacing  the  escape  wheel  with  one  of  correctly  formed 
teeth  and  size  is  the  best  means  at  our  disposal. 


CHAPTER    XIII. 

THE   DETACHED   LEVER    ESCAPEMENT   AS   APPLIED   TO    CLOCKS. 

As  the  clcck  repairer  is  almost  of  necessity  a  watch- 
maker, or  hopes  to  become  one,  and  as  he  must  enter  deeply 
into  the  study  of  all  questions  pertaining  to  the  detached 
lever  in  its  various  forms  before  he  can  make  any  progress 
at  all  in  watchmaking,  it  w^ould  seem  unnecessary  to  repeat 
in  these  pages  that  which  has  already  been  so  well  said  and 
so  perfectly  drr.\vn,  described  and  illustrated  by  such  author- 
ities as  Moritz  Grossman,  Britten,  Playtner  and  the  various 
teachers  in  the  horological  schools,  to  say  nothing  of  an 
equally  brilliant  and  more  numerous  coterie  of  writers 
among  the  French,  Germans  and  Swiss,  so  that  the  reader 
is  referred  to  these  writers  for  the  mathematics  and  draw- 
ings which  already  so  fully  cover  the  technical  and  theo- 
retical properties  of  the  detached  lever  escapement.  A  few 
words  as  to  its  adaptation  to  clocks  may,  however,  not  be 
out  of  place. 

Anyone  who  sees  the  clocks  of  to-day  would  be  inclined 
to  suppose  that  the  first  clocks  wxre  constructed  with  pendu- 
lums, because  this  is  evidently  the  most  simple  and  reliable 
system  for  clocks,  and  that  the  employment  of  the  balance 
has  been  suggested  by  the  necessity  for  portable  time  pieces. 
This  is,  however,  not  the  case,  for  the  first  clocks  had  a 
verge  escapement  with  a  crude  balance  consisting  of  tw^o 
arms,  carrying  shifting  weights  for  regulation.  The  pendu- 
lum Avas  not  used  until  about  three  hundred  years  after  the 
invention  of  the  first  clock. 

After  the  invention  of  the  dead  beat  escapement,  with  its 
great  gain  in  accuracv  by  the  reduction  of  the  arc  of  pendu- 
lum oscillation,  attempts  were  made  to  combine  its  many 
virtues  with  the  necessarily  large  vibrations  of  a  balance  and 

184 


THE    MODERN    CLOCK. 


'85 


thus  get  all  the  advantages  of  both  systems.  By  placing  the 
lever  on  the  arbor  of  the  anchor,  it  was  possible  to  multiply 
the  small  angle  of  impulse  on  the  pallets  very  considerably 
at  the  balance,  and  to  make  all  connection  between  them 
cease  immediately  after  the  impulse  had  been  given.  The 
dead  beat  escapement  was  thus  converted  into  the  detached 
lever  escapement  and  the  latter  made  available  for  both 
watches   and    clocks.     Another   important    feature   of   this 


OE 


n 


u 


no: 


3E 


fl 


U 


Fig.  61.    Pin  Escapement  for  Clocks. 


escapement  is  that  when  properly  proportioned  it  will  not  set 
on  the  locking  or  lifting,  but  will  start  to  go  as  soon  as 
power  is  applied  to  the  escape  wheel  through  the  train.  This 
cannot  be  said  of  the  cylinder,  duplex,  or  detent  escape- 
ments, and  it  will  be  seen  at  once  that  this  has  an  important 
influence  upon  the  cost  of  construction,  which  must  always 
be  considered  in  the  manufacture  of  cheap  clocks  in  enor- 
mous quantities. 


l86  THE    MODERN    CLOCK. 

The  lever  escapement  with  pins  for  pallets  and  the  lifting 
planes  on  the  teeth  of  the  escape  wheel,  which  is  the  one 
usually  put  into  cheap  clocks,  is  from  the  theoretical  point 
of  view  a  very  perfect  form,  because  its  lifting  and  locking 
lake  place  at  exactly  the  same  center  distance  and  at  the 
same  angles,  which  again  allows  for  greater  latitude  in 
cheap  construction,  while  still  maintaining  a  reasonably 
accurate  rate  of  performance.  These  are  the  main  reasons 
why  the  pin  anchor  has  such  universal  use  in  cheap  clocks. 

As  this  escapement  is  generally  centered  between  the 
plates,  banking  pins  are  dispensed  with  by  extending  the 
counterpoise  end  of  the  lever  far  enough  so  that  its  crescent 
shaped  sides  will  perform  that  office  by  banking  against  the 
scape  wheel  arbor;  see  Fig.  6i.  The  fork  end  of  the  lever 
engages  with  an  impulse  pin  carried  in  the  balance  and  the 
balance  arbor  is  cut  away  to  pass  .the  guard  point  or  dart, 
thus  doing  away  with  the  roller  table.  In  other  constructions 
the  roller  table  is  supplied  in  the  shape. of  a  small  brass  collet 
which  carries  the  pin  and  has  a  notch  for  the  guard  point, 
thus  making  a  single  roller  escapement. 

The  diameter  of  the  lifting  pins  is  generally  made  equal  to 
2^  degrees  of  the  scape  wheel,  which  gives  a  lift  of  2  de- 
grees on  the  pallet  arms,  and  the  remainder  of  the  lift,  63^ 
degrees,  must  be  performed  by  the  lifting  planes 
of  the  wheel  teeth.  The  front  sides  of  the  wheel 
teeth  are  generally  made  with  15  degrees  of  draw  and  the 
lever  should  bank  when  the  center  of  the  pin  is  just  a  little 
past  the  locking  corner  of  the  tooth.  Other  details  of  the 
pin  anchor  escapement  coincide  with  the  ordinary  pallet 
form,  as  used  in  watches,  and  the  reader  is  referred  for  them 
to  the  works  of  the  various  authors  mentioned  previously. 

The  trouble  with  the  majority  of  these  clocks  is  in  the 
escapement  and  balance  pivots,  and  to  these  parts  are  we 
going  to  direct  particular  attention,  for  often,  be  it  ever  so 
clean,  the  balance  gets  up  a  sort  of  ''caterpillar  motion"  that 
is  truly  distressing,  and  if  no  more  is  done  we  may  expect 


THE    MODERN    CLOCK.  187 

a  ''come  back"  job  in  a  very  short  time.  In  taking  down 
the  movement  the  face  wheels  are  left  in  place,  but  some- 
times it  may  be  necessary  to  remove  the  "set  wheel"  of  the 
alarm  in  order  to  proceed  as  we  do.  Remove  the  screws  or 
pins  that  hold  the  plates  together  in  the  vicinity  of  the 
escapement,  leaving  the  others,  though  if  screws  they  may 
be  loosened  slightly;  pry  up  the  corner  of  the  plate  over 
the  lever  to  loosen  one  pivot  of  same  and  let  it  drop  away 
from  the  scape  wheel  sufficiently  to  let  the  wheel  revolve 
until  it  is  locked  by  a  wire  or  pegwood  previously  inserted 
in  the  train,  after  which  the  plates  can  be  pried  apart  more 
conveniently  to  permit  the  lever  being  removed  entirely,  also 
the  scape  wheel  and  the  one  next  following.  As  nickel 
clocks  differ  in  make-up,  the  operator  must,  of  course,  exer- 
cise judgment  as  to  the  work  in  hand  to  accomplish  this. 

Have  ready  a  straight-sided  tin  pail,  with  cover,  that  will 
hold  at  least  one-half  gallon  of  gasoline  and  of  diameter 
large  enough  to  receive  the  largest  brass  clock;  remove 
the  wire  or  pegwood  and  immerse  the  clock  into  the  fluid 
and  allow  it  to  run  down;  this  will  loosen  all  the  dirt  and 
gummy  oil  and  clean  the  clock  very  effectually.  Let  it  re- 
main long  enough  for  all  the  dirt  to  settle  to  the  bottom  of 
the  pail ;  then  remove  and  wipe  as  dry  as  possible  with  a 
soft  rag ;  by  having  no  binder  on  the  spring  it  is  permitted 
to  uncoil  to  its  full,  and  thereby  remove  all  gummy  oil  be- 
tween its  coils.  Now  peg  out  the  holes  of  the  wheels  re- 
moved and  of  the  lever  and 'that  portion  of  our  work  is 
complete. 

Polish  or  burnish  the  pivots  of  wheels  either  in  a  split 
chuck  in  the  lathe,  or  by  holding  in  a  pin  vise,  resting  the 
pivot  on  a  filing  block  (an  ivory  one  is  best),  and  revolving 
between  the  fingers,  using  a  smooth  back  file  for  burnishing, 
after  the  manner  of  pointing  up  a  pin  tongue,  only  let  the 
file  be  held  flat,  so  as  to  maintain  a  cylindrical  pivot  as  nearly 
as  possible.  The  scape  wheel  is  now  polished,  i.  e.,  the  teeth, 
with  a  revolving  bristle  wheel  on  a  polishing  lathe,  charged 


l88  THE    MODERN    CLOCK. 

with  kerosene  oil  and  tripoli.  This  will  smooth  up  the  teeth 
in  fine  form,  especially  those  wheels  that  work  into  a  lever 
with  pin  pallets.  Clean  the  scape  wheel  by  dipping  into 
gasoline  to  remove  all  the  oil  and  tripoli.  The  other  wheel 
may  simply  be  brushed  in  the  gasoline  or  dipped  and  then 
brushed  dry. 

We  now  turn  our  attention  to  the  lever  and  closely  ex- 
amine the  pallets  with  a  glass;  if  there  are  the  least  signs 
of  wear  upon  them  they  must  be  removed.  If  the  lever  with 
pin  pallets  it  is  better  to  remove  the  steel  pins  and  insert  new 
ones.  See  if  the  holes  in  the  anchor  where  they  are  inserted 
will  admit  a  punch  to  drive  them  out  from  the  back ;  if  not, 
open  these  holes  with  a  drill  until  the  ends  of  the  pins  are 
reached.  Put  a  hollow  stump  with  a  sufficiently  large  hole 
in  the  staking  tool,  and  by  placing  the  pins  in  the  stump 
they  can  be  driven  out  successively,  being  sure  that  the 
driving  punch  is  no  larger  than  the  pins  ;  drive  or  insert  into 
their  places  a  couple  of  needles  of  the  proper  size,  and  then 
break  off  at  correct  lengths;  this  completes  the  job  in  this 
particular  style  of  lever. 

With  the  other  style  the  job  is  not  quite  so  easy ;  with  a 
pair  of  small  round-nose  pliers  grasp  the  brass  fork  close  up 
to  the  staff  and  bend  it  back  from  the  pallets  till  it  lays 
parallel  with  the  staff;  treat  the  counter  poise  of  the  fork 
in  like  manner ;  place  a  thin  zinc  lap  into  the  lathe,  charged 
with  flour  of  emery,  and  with  the  fingers  holding  the  pallets 
grind  off  all  wheel  teeth  marks  on  both  the  impulse  and  lock- 
ing faces  of  the  pallets.  Then  polish  with  a  boxwood  lap 
charged  with  diamantine.  It  is  surprising  how  speedily  this 
can  be  done  if  laps  are  at  hand.  The  only  care  necessary 
is  not  to  round  off  the  corners  of  the  pallets,  and  as  they  are 
so  large  they  can  be  easily  held  flat  against  the  laps  with 
the  thumb  and  finger  as  before  stated.  Bend  back  the  fork 
and  counterpoise  to  their  original  position.  The  fork  must 
now  be  attended  to;  see  that  no  notches  are  worn  in  the 
horns  of  the  fork  by  the  steel  impulse  pin  in  the  balance ;   if 


THE    MODERN    CLOCK.  189 

the}^  appear  they  must  be  dressed  out  and  polished,  also  ex- 
amine and  smooth  if  necessary  the  ends  of  the  horns  that 
bank  against  the  balance  staff.  These  may  seem  small  mat- 
ters, but  they  are  often  what  cause  all  the  trouble. 

We  now  come  to  the  balance  staff  and  the  hardened 
screws  in  which  the  staff  vibrates ;  their  irregularities  are 
often  the  source  of  much  vexation,  and  there  is  only  one 
way  to  go  at  it  and  that  is  with  a  will  and  determination  to 
make  it  right.  Examine  the  points  of  the  staff  and  see  if 
they  are  in  their  normial  shapes  and  are  sharp  and  bright ;  if 
so  they  will  probably  do  their  work.  But  we  will  suppose 
we  have  a  bad  case  in  hand  and  will  therefore  treat  it  thor- 
oughly according  to  our  method.  We  find  the  staff  is  large 
in  diameter  and  the  ends  are  very  blunt;  the  notch  in  the 
center  has  a  burr  on  each  side  as  hard  as  glass,  making  an 
admirable  cause  for  catching  the  horns  of  the  fork  in  some 
of  the  vibrations  or  in  a  certain  position ;  also  the  round  part 
of  the  staff  back  of  the  notch  is  rough  and  looks  as  if  it  never 
had  been  finished,  and,  in  fact,  it  has  not,  for  it  truly  appears 
as  if  half,  if  not  all,  the  nickel  clocks  are  made  to  be  finished 
by  the  watchmaker.  -  Remove  the  hairspring  and  place  the 
staff  between  the  jaws  of  your  bench  vise,  with  the  jaws 
close  up  to  the  staff,  but  not  gripping  it,  the  balance  ''hub" 
resting  on  the  jaws  with  the  impulse  pin  also  down  between 
the  jaws.  Have  a  block  of  brass  about  one-fourth  inch 
square ;  rest  it  on  top  of  the  staff,  or  on  its  pivot  end,  if  it 
may  so  be  called,  holding  it  with  the  thumb  and  finger  of 
the  left  hand.  Strike  this  block  with  a  hammer  and  drive 
out  the  staff ;  a  hollow  punch  is  apt  to  be  split  in  doing  this, 
and  as  the  pivot  is  to  be  re-pointed  no  harm  will  be  done  to 
ihc  pivot  or  to  the  end  of  the  staff.  Draw  the  temper  so  it 
will  work  easily,  insert  into  a  split  chuck  and  turn  up  new 
points ;  have  them  long  and  tapering,  that  is,  turn  the  points 
to  a  long  slant  from  the  end  of  the  staff  to  the  body  of  same, 
or  at  least  twice  as  much  taper  as  they  generally  have; 
polish  off  the  back  of  the  notch  or  round  part  of  the  staff 


190 


THE    MODERN    CLOCK. 


with  an  oil  stone  slip.  Remove  from  the  chuck,  smear  all 
over  with  powdered  boracic  acid  by  first  wetting  the  staff  in 
water,  and  then  heat  to  a  bright  red  and  plunge  straight  into 
water;  it  will  now  be  white  and  hard;  draw  the  temper 
from  the  staff  in  the  vicinity  of  the  notch,  leaving  the  pivot 
points  hard  as  before;  re-insert  into  the  chuck  and  with 
diamantine  polish  the  points  and  also  around  the  staff  in  the 
vicinity  of  the  notch.  The  drawing  of  the  temper  from  the 
center  of  the  staff  to  a  spring  temper  is  to  make  it  less 
liable  to  breakage  while  driving  on  the  balance.  Fasten 
the  staff  tight  in  the  vise  and  with  a  rather  stout  brass  tube, 
large  enough  to  step  over  the  largest  staff,  drive  on  the 
balance  to  its  former  position. 

If  the  workman  has  a  pivot  polisher  with  a  large  lap,  the 
job  may  be  done,  without  softening  the  staff  or  removing 
the  balance,  by  grinding  the  pivots.  In  turning  the  staff  we 
often  find  it  almost  impossible  to  hold  true.  We  straighten 
the  best  we  can  and  then  turn  up  our  pivots,  and  as  long  as 
the  untruth  of  the  staff  will  not  cause  the  balance  to  wabble 
to  such  an  extent  as  to  give  us  a  headache  or  cause  us  to 
look  cross-eyed  it  will  do.  W«  do  not -wish  to  be  misunder- 
stood or  to  give  the  impression  that  we  go  on  the  principle 
of  "good  enough" ;  but  as  gold  dollars  cannot  be  bought  for 
seventy-five  cents,  neither  can  a  workman  devote  the  time  to 
have  everything  perfect  for  fifty  cents ;  and  for  this  very 
reason  do  they  come  in  such  an  unfinished  state  from  the 
mianufacturers. 

Next  see  if  the  two  screws  in  which  the  balance  vibrates 
have  properly  cut  countersinks ;  if  rough  or  irregular,  better 
at  once  draw  the  temper,  re-drill  with  a  sharp-angled  drill 
and  again  harden. 

Occasionally  a  bunch  of  these  clocks  will  come  in  with 
both  pivots  and  cones  badly  rusted.  This  has  generally  been 
caused  by  acid  pickling,  or  some  sort  of  chemical  harden- 
ing at  the  factory ;  the  acid  or  alkali  gets  into  the  pores  of 
the  steel  and  comes  out  after  the  clock  has  been  shipped. 


THE    MODERN    CLOCK. 


191 


They  are  generally  made  in  such  quantities  that  fifty  or  a 
hundred  thousand  of  them  have  been  distributed  before 
finding  out  that  they  were  not  right  and  then  it  is  a  matter 
of  two  or  three  years  before  the  factory  hears  the  last  of  it. 
The  trouble  is  attributed  to  bad  oil,  or  to  anything  else  but 
the  hardening,  which  is  the  real  cause,  and  the  expense  of 
taking  back  and  refitting  the  balance  arbors  and  cones, 
paying  freight  both  ways .  and  standing  the  abuse  of  dis- 
gruntled jewelers,  goes  on  until  life  becomes  anything  but 
a  -bed  of  roses.  Every  jeweler  should  warn  the  factory  im- 
mediately on  finding  rust  in  the  cones  of  a  shipment  of  new 
clocks  and  not  attempt  to  fix  them  himself,  as  such  a  fault 
cannot  be  discovered  at  the  factory  and  every  day  it  con- 
tinues means  more  thousands  of  clocks  distributed  that  will 
give  trouble. 

Our  clock  is  now  ready  to  be  put  together.  Wind  up  the 
spring  and  slip  on  the  binder;  then  put  in  the  wheels  and 
lever ;  then  adjust  the  balance  and  hairspring  to  their  proper 
places,  slightly  wind  the  mainspring  and  then  see  (by  bring- 
ing either  horn  against  the  staff)  whether  it  sticks  and  holds 
the  balance ;  if  so,  shorten  the  fork  slightly  by  bending ;  try 
this  until  the  balance  and  fork  act  perfectly  free  and  safe. 
Slightly  oil  the  balance  pivots;  an  excess  will  only  gather 
dust  and  prove  detrimental,  as  the  countersinks  form  an  ad- 
mirable place  for  holding  the  dust.  Now  oil  the  remaining 
parts  and  we  are  sadly  mistaken  if  our  clock  does  not  make 
a  motion  that  will  be  gratifying. 

The  foregoing  process  may  seem  tedious  and  uncalled  for 
and  too  close  m.ention  made  of  the  lesser  portions  of  the 
work,  but  we  must  not  ''despise  the  day  of  small  things," 
and  as  we  are  watchmakers,  we  are  expected  to  do  this 
work,  even  though  troublesome  and  the  pay  small ;  we 
should  also  bear  in  mind  that  if  we  only  make  a  nickel 
clock  run  and  keep  fair  time,  it  will  be  a  large  advertise- 
ment, and  possibly  repay  tenfold.     It  takes  only  an  hour  to 


192  THE    MODERN    CLOCK. 

do  this  job  complete,  while  in  many  cases  only  the  balance 
staff  needs  attention. 

Sometimes  such  a  clock  will  be  apparently  all  right  me- 
chanically but  will  continue  to  lose  time ;  then  it  is  probable 
'that  the  balance  does  not  make  the  proper  number  of  vibra- 
tions, which  causes  the  clock  to  lose  time.  There  is  one  way 
to  tell  this,  which  will  soon  locate  the  trouble:  count 
the  train  to  ascertain  the  number  of  vibrations  the  balance 
should  make  in  one  minute.  You  do  this  by  counting  the 
number  of  teeth  in  the  center  wheel,  which  we  will  say  is  48; 
third  wheel  48;  fourth  wheel,  45;  escape,  15.  Multiply  all 
teeth  together,  which  give  us  48x48x45x15  =  1,555,200. 
Now  count  the  leaves  in  the  third  wheel  pinion,  which  is 
6 ;  fourth,  6 ;  escape,  6.  Multiply  these  together,  6x6x6  = 
216;  now  divide  the  leaves  into  the  teeth,  1,555,200^-216 
=  7,200,  w^hich  is  the  number  of  whole  vibrations  some  An- 
sonia  alarm  clocks  make  in  one  hour.  Dividing  7,200  by  60 
gives  us  120,  the  number  of  vibrations  per  minute.  Now  the 
balance  must  make  120  vibrations  in  one  minute,  counting 
the  balance  going  one  way.  If  the  balance  only  vibrates 
118,  the  clock  will  lose  time  and  the  hairspring  must  be 
taken  up  or  made  shorter,  until  it  makes  the  required  num- 
ber of  vibrations.  If  it  should  vibrate  122  the  clock  would 
gain  ^nd  the  hairspring  should  be  let  out. 

Find  out  the  number  of  vibrations  your  balance  should 
make  and  work  accordingly;  and  if  you  find  that  the  bal- 
ance makes  the  proper  number  of  vibrations  in  one  minute, 
then  the  trouble  must  lie  in  the  center  post,  which  has  not 
enough  friction  to  carry  the  hands  and  dial  wheels,  or  the 
wheel  that  gears  into  the  hour  wheel  and  regulates  the 
alarm  hand  is  too  tight  and  holds  back  the  hands.  You 
should  find  some  trouble  about  these  wheels  or  center  post, 
for  where  a  balance  makes  the  proper  number  of  vibrations 
in  one  minute,  the  minute  hand  cannot  help  going  around 
if  everything  else  is  correct. 


THE    MODERN    CLOCK. 


193 


Fig.  62  illustrates  the  escapement  of  the  Western  Clock 
Manufacturing  Company  for  their  cheap  levers.  It  has 
hardened  steel  pallets  placed  in  a  mould  and  the  fork  cast 
around  them,  thus  insuring  exact  placing  of  the  pallets,  and 
the  company  claim  that  they  thus  secure  a  detached  lever 
escapement  with  all  the  advantages  of  hardened  and  polished 
pallets  at  a  minimum  cost. 

Mr.  F.  Dauphin,  of  Cassel,  Germany,  on  page  387  of  Der 
Deutsche  Uhrmacher  Zeitung,  1905,  has  described  a  serious 
fault  of  some  of  the  cheap  American  alarm  clocks  in  the 


Fig.  62. 

depthings  of  the  escapements  and  how  he  remedied  it  by 
changing  the  position  of  the  pins.  It  is  to  be  regretted  that 
Mr.  Dauphin  did  not  state  the  measurements  of  the  parts  as 
nearly  as  possible  in  this  article  and  also  give  the  manu- 
facturer's name,  simply  to  enable  others  not  as  skilled  as  he 
is  to  do  what  I  would  do  in  such  a  case ;  namely,  to  return 
it  to  the  jobber  and  get  a  new  and  correct  movement  in  its 
stead  free  of  charge.  The  American  clock  manufacturers 
are  very  liberal  in  this  respect  and  never  hesitate  to  take 
back  a  movement  that  was  not  correct  when  it  leff  the  fac- 
tory, even  when  the  customer,  in  the  attempt  to  correct  it, 
has  spoiled  it ;  spoiled  or  not,  it  goes  to  the  waste  pile  any- 
way, when  it  reaches  the  factory.  I  seriously  doubt  the 
ability  of  the  average  watch  repairer  to  correctly  change  the 
position  of  the  pins  as  suggested;  and  to  change  the  center 
of  action  of  the  lever  is  certainly  a  desperate  job.  I  here- 
vvith  give  a  correct  drawing  of  an  escape  wheel  and  lever, 


194 


THE    MODERN    CLOCK. 


such  as  are  used  in  the  above  cited  clocks,  made  from  meas- 
urements of  the  parts  of  a  clock.  The  drawing  is,  of 
course,  enlarged.  The  measurements  are:  Escape  wheel, 
actual  diameter,  i8.ii  mm.;  original  diameter,  17  mm.; 
fever,  from  pin  to  pin,  outside,  9.3  mm.;  distance  of  cen- 
ters of  wheel  and  lever,  lo.o  mm.  I  found  that  all  these 
measurements  almost  exactly  agree  with  Grossmann's 
tables,  and  I  do  not  doubt  at  all  that  they  were  taken  from 


them.  There  is  only  one  mistake  visible,  which  is  in  the 
shape  of  the  escape  teeth,  and  I  fail  to  see  why  this  was 
overlooked  by  those  in  charge  at  the  factory:  the  drazv  is 
insufficient.  It  is  only  from  seven  to  eight  degrees,  when 
it  should  be  fifteen  degrees.  I  show  this  at  tooth  A,  in  the 
drawing,  where  you  can  see  both  dotted  lines,  measuring 
the  angle  of  draw ;  line  C  as  it  is  and  line  B  as  it  should  be. 
Notwithstanding  the  deficient  draw,  this  escapement  will 
work  safely  as  long  as  the  pivot  holes  are  not  too  large,  or 
t\^orn  sideways ;  but  if  you  want  to  make  it  safe  you  should 
file  the  locking  faces  of  teeth  slightly  under ;  even  if  you 


THE    MODERN    CLOCK.  I95 

do  not  make  a  model  job,  you  have  remedied  the  fault. 
Make  a  disk  of  i8.ii  mm.  diameter,  put  it  on  the  arbor  of 
the  wheel  and  lay  a  straight  edge  from  the  point  of  the 
tooth  to  the  center  of  the  disk,  so  as  to  see  how  much  it 
needs  to  be  filed  away.  Even  if  this  undercutting  is  not 
very  true  it  will  go. 

To  Measure  Wheels  with  Odd  Numbers  of  Teeth. 
— This  is  a  job  that  so  frequently  comes  to  the  watchmaker 
who  has  to  replace  wheels  or  pinions  that  the  following 
simple  method  should  be  generally  appreciated.  It  de- 
pends upon  the  fact  that  the  radius  of  a  circle,  R,  Fig.  64, 
equals  the  versed  sine  E  (dotted)  plus  the  cosine  B.  If 
we  stand  such  a  wheel  on  the  points  of  the  teeth,  A  C,  and 
measure  it  we  shall  get  the  length  of  the  line  T  B  only, 
when  what  we  really  need  is  the  length  of  the  lines  T  B  E, 
to  give  us  the  real  diameter  for  our  wheel,  and  E  we  find  has 
been  cut  away,  so  that  we  cannot  measure  it.  Say  it  is  a 
15-tooth  escape  wheel,  then  by  standing  the  old  wheel  up  on 
the  anvil  of  a  vertical  micrometer,  resting  it  on  two  of  its 
teeth,  as  shown  in  Fig.  64,  the  measuring  screw  can  be 
brought  in  contact  with  the  tooth  diametrically  opposite  the 
space  between  the  two  teeth  on  the  anvil,  and  a  measure- 
ment taken,  which  will  be  less  than  the  full  diameter  by  the 
versed  sine  of  12  degrees  (half  the  angle  included  between 
two  adjoining  teeth).  By  bringing  each  tooth  in  succession 
to  the  top,  such  a  wheel  could  be  measured  in  fifteen  differ- 
ent directions,  which  would  vary  slightly,  owing  to  the  fact 
that  some  of  the  teeth  may  be  bent  a  little,  but  the  mean 
of  these  measures  should  be  what  the  wheel  would  measure 
were  the  teeth  in  their  original  shape.  If  a  tooth  was  badly 
bent  the  three  measures  in  which  it  was  involved  could  be 
rejected,  and  the  mean  of  the  other  twelve  measures  taken 
as  the  correct  value  and  found  to  be,  we  will  say,  0.732  inch. 
Consulting  a  table  of  natural  sines  the  cosine  of  12  degrees 
is   found  to  be  0.97815,   which   subtracted    from    i    gives 


196 


THE    MODERN    CLOCK. 


0.02185  as  the  versed  sine.  Multiplying  this  by  0.36  inch 
(practically  one-half  of  our  measured  0.732)  to  get  the 
approximate  radius  of  the  wheel,  we  get  0.008  inch,  the 
amount  to  be  added  to  the  micrometer  measurement  in 
order  to  get  the  diameter  of  the  blank. 

At  first  sight  it  may  appear  like  a  vicious  principle  that 
we  must  know  the  radius  of  the  wheel  before  we  can  deter- 


oi.    Cjctting  the  fuU  diameter. 


mine  the  value  of  the  correction  in  question,  but  we  only 
need  to  know  the  radius  approximately  in  order  to  determine 
the  correction  very  closely,  an  error  of  1-20  inch  in  the  as- 
sumed value  of  the  radius  producing  an  error  of  only  o.ooi 
inch  in  the  value  of  the  correction. 

This  method  can  of  course  be  applied  to  all  wheels  and 
pinions  to  get  the  size  of  the  blank;  with  other  wheels  than 
escape  wheels,  where  the  pitch  line  and  the  full  diameter 
do  not  coincide,  the  addendum  may  be  subtracted  from  the 
full  diameter  to  get  the  pitch  line. 

Cutters  for  Clock  Trains. — In  cutting  escape  wheels 
or  others  with  wnde  space  between  the  teeth,  it  is  a  matter 


THE    MODERN    CLOCK. 


97 


of  some  difficulty  with  many  people  to  enable  them  to  set 
the  cutter  properly. 

Mr.  E.  A.  Sweet  calls  attention  to  the  fact  that  if  a  cutter 
be  set  so  that  its  center  touches  the  circumference  of  the 
wheel  to  be  cut,  said  cutter  will  be  in  the  proper  position  for 
work.  For  instance,  if  an  escape  wheel  is  to  be  cut,  it  is 
sufficient  to  set  the  cutter  in  such  a  manner  that  that  portion 
of  the  cutter  forming  the  bottom  of  the  cut  touch  the  cir- 
cumference of  the  blank  at  the  center  of  the  cutter.  It  may 
then  be  backed  off  and  fed  in  with  the  certainty  of  being 
properly  placed. 


CHAPTER   XIV. 

PLATES^    PIVOTS    AND    TIME   TRAINS. 

Before  going  further  with  the  mechanism  of  our  clocks 
we  will  now  consider  the  means  by  which  the  various  mem- 
bers are  held  in  their  positions,  namely,  the  plates.  Like 
most  other  parts  of  the  clock  these  have  undergone  various 
changes.  They  have  been  made  of  wood,  iron  and  brass 
and  have  varied  in  shapes  and  sizes  so  much  that  a  great 
deal  may  be  told  concerning  the  age  of  a  clock  by  examining 
the  plates. 

Most  of  the  wooden  clocks  had  wooden  plates.  The 
English  and  American  movements  were  simply  boards  of 
oak,  maple  or  pear  with  the  holes  drilled  and  bushed  with 
brass  tubes — full  plates.  The  Schwarzwald  movements 
were  generally  made  with  top  and  bottom  boards  and 
stanchions,  mortised  in  between  them  to  carry  the  trains, 
which  were  always  straight-line  trains.  The  rear  stanchions 
were  glued  in  position  and  the  front  ones  fitted  friction- 
tight,  so  that  they  could  be  removed  in  taking  down  the 
clock.  This  gave  a  certain  convenience  in  repairmg,  as,  for 
instance,  the  center  (time)  train  could  be  taken  down  with- 
out disturbing  the  hour  or  quarter  trains,  or  vice  versa. 
Various  attempts  have  been  made  since  to  retain  their  con- 
venience with  brass  plates,  but  it  has  always  added  so  much 
to  the  cost  of  manufacture  that  it  had  to  be  abandoned. 

The  older  plates  were  cast,  smoothed  and  then  ham- 
mered to  compact  the  metal.  The  modern  plate  is  rolled 
much  harder  and  stiflfer  and  it  may  consequently  be  much 
thinner  than  was  formerly  necessary.  The  proper  thickness 
of  a  plate  depends  entirely  upon  its  use.  Where  the  move- 
ment rests  upon  a  seat  board  in  the  case  and  carries  the 


THE    MODERN    CLOCK.  I99 

weight  of  a  heavy  penduhim.  attached  u  one  of  the  plates 
they  must  be  made  stiff  enough  to  furnish  a  rigid  support 
for  the  pendulum,  and  we  find  them  thick,  heavy  and  with 
large  pillars,  well  supported  at  the  corners,  so  as  to  be  very 
stiff  and  solid.  An  example  of  this  may  be  seen  in  that 
class  of  regulators  which  carry  the  pendulum  on  the  move- 
ment. Where  the  pendulum  is  light  the  plates  may  there- 
fore be  thin,  as  the  only  other  reason  necessary  for  thick- 
ness is  that  they  may  provide  a  proper  length  of  bearing  for 
the  pivots,  plus  the  necessary  countersinking  to  retain  the 
oil. 

In  heavy  machinery  it  is  unusual  to  provide  a  length  of 
box  or  journal  bearing  of  more  than  three  times  the  diam- 
eter of  the  journal.  In  most  cases  a  length  of  twice  the 
diameter  is  more  than  sufficient;  in  clock  and  other  light 
work  a  "square"  bearing  is  enough ;  that  is  one  in  which 
the  length  is  equal  to  the  diameter.  In  clocks  the  pivots  are 
of  various  sizes  and  so  an  average  must  be  found.  This  is 
accomplished  by  using  a  plate  thick  enough  to  furnish  a 
proper  bearing  for  the  larger  pivots  and  countersinking  the 
pivot  holes  for  the  smaller  pivots  until  a  square  bearing  is 
obtained.  This  countersinking  is  shaped  in  such  a  manner 
as  to  retain  the  oil  and  as  more  of  it  is  done  on  the  smaller 
and  faster  moving  pivots,  where  there  is  the  greatest  need 
of  lubrication,  the  arrangement  works  out  very  nicely,  and 
it  will  be  seen  that  with  all  the  lighter  clocks  very  thin  plates 
may  be  employed  while  still  retaining  a  proper  length  of 
bearing  in  the  pivot  holes. 

The  side  shake  for  pivots  should  be  from  .002  to  .004  of 
an  inch;  the  latter  figure  is  seldom  exceeded  except  in 
cuckoos  and  other  clocks  having  exposed  w^eights  and 
pendulums.  Here  much  greater  freedom  is  necessary  as 
the  movement  is  exposed  to  dust  which  enters  freely  at  the 
holes  for  pendulum  and  weight  chains,  so  that  such  a  clock 
would  stop  if  given  the  ordinary  amount  of  side  shake. 


20O  THE    MODERN    CLOCK. 

We  are  afraid  that  many  manufacturers  of  the  ordinary 
American  clock  aim  to  use  as  thin  brass  as  possible  for 
plates  without  paying  too  much  attention  to  the  length  of 
bearing.  If  a  hole  is  countersunk  it  will  retain  the  oil 
when  a  flat  surface  will  not.  The  idea  of  countersinking  to 
obtain  a  shorter  bearing  will  apply  better  to  the  fine  clocks 
than  to  the  ordinary.  In  ordinary  clocks  the  pivots  must  be 
longer  than  the  thickness  of  the  plates  for  the  reason  that 
freight  is  handled  so  roughly  that  short  pivots  will  pop  out 
of  the  plates  and  cause  a  lot  of  damage,  provided  the  springs 
are  wound  when  the  rough  handling  occurs. 

It  will  be  seen  by  reference  to  Chapter  VII  (the  mechan- 
ical elements  of  gearing),  Figs.  21  to  25,  that  a  wheel  and 
pinion  are  merely  a  collection  of  levers  adapted  to  con- 
tinuous work,  that  the  teeth  may  be  regarded  as  separate 
levers  coming  into  contact  with  each  other  in  succession; 
this  brings  up  two  points.  The  first  is  necessarily  the  rela- 
tive proportions  of  those  levers,  as  upon  these  will  depend 
the  power  and  speed  of  the  motion  produced  by  their  action. 
The  second  is  the  shapes  and  sizes  of  the  ends  of  our  levers 
so  that  they  shall  perform  their  work  with  as  little  friction 
and  loss  of  power  as  possible. 

To  Get  Center  Distances. — As  the  radii  and  circum- 
ferences of  circles  are  proportional,  it  follows  that  the 
lenoths  of  our  radii  are  merely  the  lengths  of  our  levers 
'"^ce  Fig,  24),  and  that  the  two  combined  (the  radius  of 
the  wheel,  plus  that  of  the  pinion)  will  be  the  distance  at 
which  we  must  pivot  our  levers  (our  staffs  or  arbors  of  our 
wheels)  in  order  to  maintain  the  desired  proportions  of 
their  revolution.  Consequently  we  can  work  this  rule  back- 
wards or  forwards. 

For  instance  if  we  have  a  wheel  and  pinion  which  must 
work  together  in  the  proportion  of  7^  to  i  ;  then  7^  -f-  i 
=r  Sy2;  and  if  we  divide  the  space  between  centers  into  8>4 
spaces  we  will  have  one  of  these  spaces  for  the  radius  of  the 


THE    MODERN    CLOCK.  20I 

i?ifch  circle  of  the  pinion  and  7^.  for  the  pitch  circle  of  the 
wheel,  Fig.  65.  This  is  independent  of  the  number  of  teeth 
so  long  as  the  proportions  be  observed ;  thus  our  pinion  may 
have  eight  teeth  and  the  wheel  sixty,  60  -f-  8  :=  7.5,  or 
75  -^  10  =:  7.5,  or  90-f-  12  =  7.5,  or  any  other  combination 
of  teeth  which  will  make  the  correct  proportion  between 
them  and  the  center  distances.  The  reason  is  that  the  teeth 
are  added  to  the  wheel  to  prevent  slipping,  and  if  they  did 
not  agree  with  each  other  and  also  with  the  proportionate 
distance  between  centers  there  would  be  trouble,  because 
the  desired  proportion  could  not  be  maintained. 

Now  we  can  also  work  this  rule  backwards.  Say  we 
have  a  wheel  of  80  teeth  and  the  pinion  has  10  leaves  but 
they  do  not  work  together  well  in  the  clock.  Tried  in  the 
depthing  tool  they  work  smoothly.  80  -^-  10  :=  8,  conse- 
quentty  our  center  distance  must  be  as  8  and  i.  8  -]-  i  =  95 
the  wheel  must  have  8  parts  and  the  pinion  i  part  of  the 
radius  of  the  pitch  circle  of  the  wheel.  IMeasure  carefully 
the  diameter  of  the  pitch  circle  of  the  v^/heel ;  half  of  that  is 
the  pitch  radius,  and  nine-eighths  of  the  pitch  radius  is  the 
proper  center  distance  for  that  wheel  and  pinion. 

Say  we  have  lost  a  wheel ;  the  pinion  has  12  teeth  and  we 
know  the  arbor  should  go  seven  and  one-half  times  to  one 
of  the  missing  wheel;  we  have  our  center  distances  estab- 
lished by  the  pivot  holes  which  are  not  worn;  what  size 
should  the  wheel  be  and  how  many  teeth  should  it  have  ? 
12  X  7-5  =  90,  the  number  of  teeth  necessary  to  contain 
the  teeth  of  the  pinion  7.5  times.  7.5  -[-  i  =  8.5,  the  sum  of 
the  center  distances ;  the  pitch  radius  of  the  pinion  can  be 
closely  measured ;  then  7.5  times  that  is  the  pitch  radius  of 
the  missing  wheel  of  90  teeth.  Other  illustrations  with  other 
proportions  could  be  added  indefinitely  but  we  have,  we 
think,  said  enough  to  make  this  point  clear. 

Conversion  of  Numbers. — There  is  one  other  point 
which  sometimes  troubles  the  student  who  attempts  to  fol- 


202 


THE    MODERN    CLOCK. 


low  the  expositions  of  this  subject  by  learned  writers  and 
that  is  the  fact  that  a  mathematician  will  take  a  totally 
difterent  set  of  numbers  for  his  examples,  without  explain- 
ing why.  If  you  don't  know  why  you  get  confused  and  fail 
to  follow  him.  It  is  done  to  avoid  the  use  of  cumbersome 
fractions.  To  use  a  homely  illustration:  Say  we  have 
one  foot,  six  inches  fo^  cur  wheel  radius  and  4.5  inches  for 


Fig.  G5.    Spacing  off  center  di-tances;  c,  ce:;  cr  of  wlieel;  e,  pitch  circle; 
d,  dedenduni;  b,  addendum;  a,  center  of  pinion. 


our  pinion  radius.  If  we  turn  the  foot  into  inches  we  have 
18  inches.  18 -f- 4.5  =  4,  which  is  simpler  to  work  with. 
Now  the  same  thing  can  be  done  with  fractions.  In  the 
above  instance  we  got  rid  of  our  larger  unit  (the  foot)  by 
turning  it  into  smaller  units  (inches)  so  that  we  had  only 
one  kind  of  units  to  work  with.  The  same  thing  can  be  done 
with  fractions ;  for  instance,  in  the  previous  example  we 
can  get  rid  of  our  mixed  numbers  by  turning  everything 


THE    MODERN    CLOCK.  203 

into  fractions.  Eighteen  inches  equals  36  halves  and  4.5 
equals  9  halves ;  then  36  -f-  9  =  4.  This  is  called  the  con- 
version of  numbers  and  is  done  to  simplify  operations.  For 
instance  in  watch  work  we  may  find  it  convenient  to  turn  all 
our  figures  into  thousands  of  a  millimeter,  if  we  are  using 
a  millimeter  gauge.  Say  we  have  the  proportions  of  7.5  to 
I  to  maintain,  then  turning  all  into  halves,  7^.  X  2  =  15 
and  1X2  =  2.  15  +  2=17  parts  for  our  center  distance, 
of  which  the  pitch  radius  of  the  pinion  takes  2  parts  and  that 
of  the  wheel  15. 

The  Shapes  of  the  Teeth. — The  second  part  of  our 
problem,  as  stated  above,  is  the  shapes  of  the  ends  of  our 
levers  or  the  teeth  of  our  wheels,  and  here  the  first  consid- 
eration which  strikes  us  is  that  the  teeth  of  the  wheels  ap- 
proach each  other  until  they  meet;  roll  or  slide  upon  each 
other  until  they  pass  the  line  of  centers  and  then  are  drawn 
apart.  A  moment's  consideration  will  show  that  as  the 
teeth  are  longer  than  the  distance  between  centers  and  are 
securely  held  from  slipping  at  their  centers,  the  outer  ends 
must  either  roll  or  slide  after  they  come  in  contact  and  that 
this  action  will  be  much  more  severe  while  they  are  being 
driven  towards  each  other  than  when  they  are  being  drawn 
apart  after  passing  the  line  of  centers.  This  is  why  the 
engaging  friction  is  more  damaging  than  the  disengaging 
friction  and  it  is  this  butting  action  which  uses  up  the  power 
if  our  teeth  are  not  properly  shaped  or  the  center  distances 
not  right.  Generally  speaking  this  butting  causes  serious 
loss  of  power  and  cutting  of  the  teeth  when  the  pivot  holes 
are  worn  or  the  pivots  cut,  so  that  there  is  a  side  shake  of 
half  the  diameter  of  the  pivots,  and  bushing  or  closing  the 
holes,  or  new  and  larger  pivots  are  then  necessary.  This  is 
for  common,  work.  For  fine  work  the  center  distances 
should  be  restored  long  before  the  wear  has  reached  this 
point. 


204  THE    MODERN    CLOCK. 

If  we  take  two  circular  pieces  of  any  material  of  different 
diameters  and  arrange  them  so  that  each  can  revolve  around 
its  center  with  their  edges  in  contact,  then  apply  power  to 
the  larger  of  the  two,  we  find  that  as  it  revolves  its  motion 
i-s  imparted  to  the  other,  which  revolves  in  the  opposite 
direction,  and,  if  there  is  no  slipping  between  the  two  sur- 
faces, with  a  velocity  as  much  greater  than  that  of  the  larger 
disc  as  its  diameter  is  exceeded  by  that  of  the  larger  one. 
We  have,  then,  an  illustration  of  the  action  of  a  wheel  and 
pinion  as  used  in  timepieces  and  other  mechanisms.  It 
would  be  impossible,  however,  to  prevent  slipping  of  these 
smooth  surfaces  on  each  other  so  that  power  (or  motion) 
would  be  transmitted  by  them  very  irregularly.  They  simply 
represent  the  "pitch"  circles  or  circles  of  contact  of  these 
two  mobiles.  If  now  we  divide  these  two  discs  into  teeth 
so  spaced  that  the  teeth  of  one  will  pass  freely  into  the 
spaces  of  the  other  and  add  such  an  amount  to  the  diameter 
of  the  larger  that  the  points  of  its  teeth  extend  inside  the 
pitch  circle  of  the  smaller,  a  distance  equal  to  about  i^ 
times  the  width  of  one  of  its  teeth,  and  to  the  smaller  so 
that  its  teeth  extend  inside  the  larger  one-half  the  width  of 
a  tooth,  the  ends  of  the  teeth  being  rounded  so  as  not  to 
catch  on  each  other  and  the  centers  of  revolution  being  kept 
the  same  distance  apart,  on  applying  power  to  the  larger  of 
the  two  it  will  be  set  in  motion  and  this  motion  will  be  im- 
parted to  the  smaller  one.  Both  will  continue  to  move  with 
the  same  relative  velocity  as  long  as  sufficient  power  is 
applied.  Other  pairs  of  mobiles  may  be  added  to  these  to 
infinity,  each  addition  requiring  the  application  of  increased 
power  to  keep  it  in  motion. 

These  pairs  of  mobiles  as  applied  to  the  construction  of 
timepieces  are  usually  very  unequal  in  size  and  the  larger 
is  designated  as  a  "wheel"  while  the  smaller,  if  having  less 
than  20  teeth,  is  called  a  "pinion"  and  its  teeth  "leaves." 
Now  while  we  have  established  the  principle  of  a  train  of 
wheels  as  used  in  various  mechanisms,  our  gearing  is  very 


THE    MODERN    CLOCK. 


205 


defective,  for  while  continuous  motion  may  be  transmitted 
through  such  a  train,  we  will  find  that  to  do  so  requires 
the  application  of  an  impelling  force  far  in  excess  of  what 
should  be  required  to  overcome  the  inertia  of  the  mobiles, 
and  the  amount  of  friction  unavoidable  in  a  mechanism 
where  some  of  the  parts  move  in  contact  with  others. 

This  excess  of  power  is  used  in  overcoming  a  friction 
caused  by  improperly  shaped  teeth,  or  when  formed  thus  the 
teeth  of  the  wheel  come  in  contact  with  those  of  the  pinion 
and  begin  driving  at  a  point  in  front  of  what  is  known  as  the 
"line  of  centers,"  i.  e.,  a  line  drawn  through  the  centers  of 
revolution  of  both  mobiles,  and  as  their  motion  continues  the 
driven  tooth  slides  on  the  one  impelling  it  toward  the  center 
of  the  wheel.  When  this  line  is  reached  the  action  is  re- 
versed and  the  point  of  the  driving  tooth  begins  sliding  on 
the  pinion  leaf  in  a  direction  away  from  the  center  of  the 
pinion,  which  action  is  continued  until  a  point  is  reached 
where  the  straight  face  of  the  leaf  is  on  a  line  tangential  to 
the  circumference  of  the  wheel  at  the  point  of  the  tooth.  It 
then  slips  off  the  tooth,  and  the  driving  is  taken  up  on  an- 
other leaf  by  the  next  succeeding  tooth.  The  sliding  action 
which  takes  place  in  front  of  the  line  of  centers  is  called 
"engaging,"  that  after  this  line  has  been  passed  "disengag- 
ing" friction. 

Now  we  know  that  in  the  construction  of  timepieces,  fric- 
tion and  excessive  motive  power  are  two  of  the  most  potent 
factors  in  producmg  disturbances  in  the  rate,  and  that,  while 
som.e  friction  is  unavoidable  in  any  mechanism,  that  which  we 
have  just  described  may  be  almost  entirely  done  away  with. 
Let  us  examine  carefully  the  action  of  a  wheel  and  pinion, 
and  we  will  see  that  only  that  part  of  the  wheel  tooth  is  used, 
which  is  outside  the  pitch  circle,  while  the  portion  of  the 
pinion  leaf  on  which  it  acts  is  the  straight  face  lying  inside 
this  circle,  therefore  it  is  to  giving  a  correct  shape  to  these 
parts  we  must  devote  our  attention.  If  we  form  our  pinion 
leaves  so  that  the  portion  of  the  leaf  inside  the  pitch  circle 


206 


THE    MODERN    CLOCK, 


is  a  straight  line  pointing  to  the  center,  and  give  that  por- 
tion of  the  wheel  tooth  lying  outside  the  pitch  circle  (called 
the  addenda,  or  ogive  of  the  tooth)  such  a  degree  of  curva- 
ture that  during  its  entire  action  the  straight  face  of  the 
leaf  will  form  a  tangent  to  that  point  of  the  curve  which  it 


Showing  that  a  hypocycloid  of 


rcle  is  a  straight  line. 


Generating  an  epicycloid  curve  for  a  cut  pinion.  D,  generating  circle. 
Uotterl  line  epicycloid  curve.  Note  how  the  shape  varies  with  the 
thickness  of  the  tooth. 

touches,  no  sliding  action  whatever  will  take  place  after  the 
line  of  centers  is  passed,  and  if  our  pinion  has  ten  or  more 
leaves,  the  "addenda"  of  the  wheel  is  of  proper  height,  and 
the  leaves  of  the  pinion  arc  net  too  thick,  there  will  be  no 
contact  in  front  of  the  I'ne  of  centers.  With  such  a  depth 
the  only  friction  would  be  from  a  slight  adhesion  of  the 
surfaces  in  contact,  a  factor  too  small  to  be  taken  into 
consideration. 


THE    MODERN    CLOCK. 


207 


Here,  then,  we  have  an  ideal  depth.  How  shall  we  obtain 
the  same  results  in  practice?  It  is  comparatively  an  easy 
matter  to  so  shape  our  cutters  that  the  straight  faces  of  our 
pinion  leaves  will  be  straight  lines  pointing  to  the  center, 
but  to  secure  just  the  proper  curve  for  the  addenda  of  our 
wheel  teeth  requires  rather  a  more  complicated  manipula- 
tion. This  curve  does  not  form  a  segment  of  a  circle,  for  it 
has  no  two  radii  of  equal  length,  and  if  continued  would 
form,  not  a  circle,  but  a  spiral.  To  generate  this  curve,  we 
will  cut  from  cardboard,  wood,  or  sheet  metal,  a  segment  of 
a  circle  having  a  radius  equal  to  that  of  our  zvheel,  on  the 
pitch  circle,  and  a  smaller  circle  whose  diameter  is  equal  to 
the  radius  of  the  pinion,  on  the  pitch  circle.  To  the  edge  of 
the  small  circle  we  will  attach  a  pencil  or  metal  point  so  that 
it  will  trace  a  fine  mark.  Now  we  lay  our  segment  flat  on  a 
piece  of  drawing  paper,  or  sheet  metal  and  cause  the  small 
circle  to  revolve  around  its  edge  without  slipping.  We  find 
that  the  point  in  the  edge  of  the  small  circle  has  traced  a 
series  of  curves  around  the  edge  of  the  segment. 

These  curves  are  called  *V.p:cycloids,"  and  have  the  pe- 
culiar property  that  if  a  line  be  drawn  through  the  generat- 
ing point  and  the  point  of  contact  of  the  two  circles,  this  will 
always  be  at  right  angles  to  a  tangent  of  the  curve  at  its 
[)oint  of  intersection.  It  is  this  property  to  which  it  owes  its 
value  as  a  shape  for  the  acting  surface  of  a  wheel  tooth, 
for  it  is  owing  to  this  that  a  tooth  whose  acting  surface  is 
bounded  by  such  a  curve  can  impel  a  pinion  leaf  through 
the  entire  lead  with  little  sliding  action  between  the  two 
surfaces.  This,  then,  is  the  curve  on  which  we  will  form 
the  addenda  of  our  wheel  teeth. 

In  Fig.  66,  the  wheel  has  a  radius  of  fifteen  inches  and  the 
pinion  a  radius  of  one  and  one-half,  and  these  two  measure- 
ments are  to  be  added  together  to  find  the  distance  apart 
of  the  two  wheels;  16.5  inches  is  then  the  distance  that  the 
centers  of  revolution  are  apart  of  the  wheels.  Now,  the  teeth 
and  leaves  jointly  act  on  one  another  to  maintain  a  sure  and 
equable  relative  revolution  of  the  pair. 


20^  THE    MODERN    CLOCK. 

In  Fig.  66,  the  pinion  has  its  leaves  radial  to  the  center, 
inside  of  the  pitch  line  D,  and  the  ends  of  the  leaves,  or  those 
parts  outside  of  the  pitch  line,  are  a  half  circle,  and  serve  no 
purpose  until  the  depthings  are  changed  by  wear,  as  they 
never  come  in  contact  with  the  wheel ;  the  wheel  teeth  only 
touch  the  radial  part  of  the  pinion  and  that  occurs  wholly 
within  the  pitch  line.  So  in  all  pinions  above  lo  leaves  in 
number  the  addendum  or  curve  is  a  thing  of  no  moment, 
except  as  it  may  be  too  large  or  too  long.  In  many  large 
pieces  of  machinery  the  pinions,  or  small  driven  wheels, 
have  no  addendum  or  extension  beyond  their  pitch  diameter 
and  they  serve  every  end  just  as  well.  In  watches  there  is 
so  much  space  or  shake  allowed  between  the  teeth  and 
pinions  that  the  end  of  a  leaf  becomes  a  necessitv  to  guard 
against  the  pinion's  recoiling  out  of  time  and  striking  its 
sharp  corner  against  the  wheel  teeth  and  so  marring  or 
cutting  them.  In  a  similar  pair  of  wheels  in  machinery  there 
are  very  close  fits  used  and  the  shake  between  teeth  is  very 
slight  and  does  not  allow  of  recoil,  butting,  or  "running  out 
of  time." 

Running  out  of  time  is  the  sudden  stopping  and  setting 
back  of  a  pinion  against  the  opposite  tooth  from  the  one 
just  in  contact  or  propelling.  This,  with  pinions  of  sup- 
pressed ends,  is  a  fault  and  it  is  averted  by  maintaining  the 
ends. 

The  wheel  tooth  drives  the  pinion  by  coming  in  contact 
with  the  straight  flank  of  the  leaf  at  the  line  of  centers,  that 
is  a  line  drawn  through  the  centers  of  the  two  wheels ;  cen- 
ters of  revolution. 

The  curve  or  end  of  the  wheel  tooth  outside  of  the  pitch 
line  is  the  only  part  of  the  tooth  that  ever  touches  the  pinion 
and  it  is  the  part  under  friction  from  pressure  and  slipping. 
At  the  first  point  of  contact  the  tooth  drives  the  pinion  with 
the  greatest  force,  as  it  is  then  using  the  shortest  leverage  it 
has  and  is  pressing  on  the  longest  lever  of  the  leaf.  As 
this  action  proceeds,  the  tooth  is  acted  on  by  the  pinion  leaf 


THE    MODERN    CLOCK. 


209 


farther  out  on  the  curve  of  the  wheel  tooth,  thus  length- 
ening the  lever  of  the  wheel  and  at  the  same  time  the  tooth 
thus  acts  nearer  to  the  center  of  the  pinion  by  touching 
the  leaf  nearer  its  center  of  revolution. 

By  these  joint  actions'  it  will^  appear  that  the  wheel  first 
drives  with  the  greatest  force  and  then  as  its  own  leverage 
lengthens  and  its  force  consequently  decreases,  it  acts  on  a 
shorter  leverage  of  the  pinion,  as  the  end  of  a  tooth,  is  nearer 
to  the  center  of  the  pinion,  or  on  the  shortest  pinion  lever- 
age, just  as  the  tooth  is  about  ceasing  to  act. 

The  action  is  thus  shown  from  the  above  to  be  a  variable 
one,  which  starts  with  a  maximum  of  force  and  ends  with  a 
minimum.  Practically  the  variable  force  in  a  train  is  not 
recognized  in  the  escapement,  as  the  other  wheels  and  pin- 
ions making  up  the  train  are  also  in  the  same  relations  of 
maximum  and  minimum  forces  at  the  same  time,  and  thus 
this  theoretical  and  virtual  variability  of  train  force  is  to  a 
great  extent  neutralized  at  the  active  or  escaping  end  of  the 
movement. 

There  is  another  action  between  the  tooth  and  leaf  that  is 
not  easy  to  explain  without  somewhat  elaborate  sketches  of 
the  acting  parts,  and  as  this  is  not  consistent  with  such  an 
article,  we  may  dismiss  it,  and  merely  state  that  it  is  the 
one  of  maintaining  the  relative  angular  velocities  of  the  two 
wheels  at  all  times  during  their  joint  revolutions. 

In  Fig.  66  will  be  seen  the  teeth  of  the  wheel,  their 
heights,  widths  and  spacing,  and  the  epicycloidal  curves. 
Also  the  same  features  of  the  pinion's  construction.  The 
curve  on  the  end  of  the  wheel  teeth  is  the  only  curve  in 
action  during  the  rotation  between  wheel  and  pinion.  Each 
flank  (both  teeth  and  leaves)  is  a  straight  line  to  the 
center  of  each.  A  tooth  is  composed  of  two  members — the 
pillar  or  body  of  the  tooth  inside  of  the  pitch  line  and  the 
cvcloid  or  curve,  wholly  outside  of  this  line.  The  pinion 
also  has  two  members,  the  radial  flank  wholly  inside  of  the 
pitch  line,  and  its  addendum  or  circle  outside  of  this  line. 


2IO 


THE    MODERN    CI.OCK, 


A' 


yyiteelolf^ff 


I  .66 


THE    MODERN    CLOCK.  211 

In  Fig.  66  will  be  seen  a  tooth  on  the  line  of  centers  A  B, 
just  coming  in  action  against  the  pinion's  flank  and  also  one 
just  ceasing  action.  It  will  be  seen  that  the  tooth  just  enter- 
ing is  in  contact  at  the  joint  pitches,  or  radii,  of  the  two 
wheels,  and  that  when  the  tooth  has  run  its  course  and 
ceased  to  act,  that  it  will  be  represented  by  tooth  2,  Then 
the  exit  contact  will  be  at  the  dotted  line  o  o.  From  this 
may  be  seen  just  how  far  the  tooth  has,  in  its  excursion, 
shoved  along  the  leaf  of  the  pinion  and  by  the  distance  the 
line  o  o,  is  from  the  wheel's  pitch  line  G,  at  this  tooth.  No.  2, 
is  shown  the  extent  of  contact  of  the  wheel  tooth.  By  these 
dotted  lines,  then,  it  may  be  seen  that  the  tooth  has  been 
under  friction  for  nearly  its  whole  curve's  length,  while  the 
pinion's  flank  will  have  been  under  friction  contact  for  less 
than  half  this  distance.  In  brief,  the  tooth  has  moved  about 
80-100  o'f  its  curved  surface  along  the  straight  flank  .35  of 
the  surface  of  the  pinion  leaf.  From  this  relative  frictional 
surface  may  be  seen  the  reason  why  a  pinion  is  apt  to  be 
pitted  by  the  wheel  teeth  and  cut  away.  In  any  case  it 
shows  the  relation  between  the  two  friction  surfaces.  In 
part  a  wheel  tooth  rolls  as  well  as  slides  along  the  leaf,  but 
whatever  rolling  there  may  be,  the  pinion  is  also  equally 
favored  by  the  same  action,  which  leaves  the  proportions  of 
individual  friction  still  the  same. 

In  Fig.  66  may  be  seen  the  spaces  of  the  teeth  and  pinion. 
The  teeth  are  apart,  equal  to  their  own  width  and  the  depths 
of  the  spaces  are  the  same  measurement  of  their  width — that 
is,  the  tooth  (inside  of  the  pitch  line)  is  a  pillar  as  wide  as  it 
is  high  and  a  space  between  two  teeth  is  of  like  proportions 
and  extent  of  surface.  The  depth  of  a  space  between  two 
teeth  is  only  for  clearance  and  may  be  made  much  less,  as 
may  be  seen  by  the  pinion  leaf,  as  the  end  of  the  circle  does 
not  come  half  way  to  the  bottom  of  a  space. 

The  dotted  line,  o  o,  shows  the  point  at  which  the  tooth 
comes  out  of  action  and  the  pointed  end  outside  of  this  line 
might  be  cut  off  without  interfering  with  any  function  of 


212  THE    MODERN    CLOCK. 

the  tooth.  They  generally  are  rounded  off  in  common  clock 
work. 

The  pinion  is  3  inches  diameter  and  is  divided  into  twelve 
spaces  and  twelve  leaves;  each  leaf  is  two-fifths  of  the 
width  of  a  space  and  tooth.  That  is  one-twelfth  of  the  cir- 
cumference of  the  pinion  is  divided  into  five  equal  parts  and 
the  leaf  occupies  two  and  a  space  three  of  these  parts.  The 
space  must  be  greater  than  the  width  of  a  leaf,  or  the  end  of 
a  leaf  w^ould  come  in  contact  with  a  tooth  before  the  line 
of  centers  and  cause  a  jamming  and  butting  action.  Also 
the  space  is  needed  for  dirt  clearance.  As  watch  trains 
actuated  by  a  spring  do  not  have  any  reserve  force  there 
must  be  allowance  made  for  obstructions  between  the  teeth 
of  a  train  and  so  a  large  latitude  is  allowed  in  this  respect, 
more  than  in  any  machinery  of  large  caliber.  As  will  be 
seen  by  Fig.  66,  the  spans  between  the  leaves  are  deep,  much 
more  so  than  is  really  necessary,  and  a  space  at  O  C  shows 
the  bottom  of  a  space,  cut  on  a  circle  which  strengthens  a 
leaf  at  its  root  and  is  the  best  practice. 

Having  determined  the  form  of  our  curve,  our  next  step 
will  be  to  get  the  proper  proportions.  Saunier  recommends 
that  in  all  cases  tooth  and  space  should  be  of  equal  width, 
but  a  more  modern  practice  is  to  make  the  space  slightly 
wider,  say  one-tenth  where  the  curve  is  epicycloidal.  When 
the  teeth  are  cut  with  the  ordinary  Swiss  cutters,  which,  of 
course,  cannot  be  epicycloidal,  it  is  best  to  make  the  spaces 
one-seventh  wider  than  the  tooth.  This  proportion  will  be 
correct  except  in  the  case  of  a  ten-leaf  pinion,  when,  if  we 
w4sh  to  be  sure  the  driving  will  begin  on  the  line  of  centers, 
the  teeth  must  be  as  wide  as  the  spaces ;  but  in  this  case 
the  pinion  leaf  is  made  proportionately  thinner,  so  that  the 
requisite  freedom  is  thus  obtained. 

The  height  of  the  addenda  of  the  wheel  teeth  above  the 
pitch  circle  is  usually  given  as  one  and  one-eighth  times  the 
width  of  a  tooth.  While  this  is  approximately  correct,  it  is 
not  entirelv  so,  for  the  reason  that  as  we  use  a  circle  whose 


THE    MODERN    CLOCK.  213 

diameter  is  equal  to  the  pitch  radius  of  the  pinion  for  gen- 
erating the  curve,  the  height  of  the  addenda  would  be  differ- 
ent on  the  same  wheel  for  each  different  numbered  pinion. 
So  that  if  a  wheel  of  60  were  cut  to  drive  a  pinion  of  8,  the 
curve  of  this  tooth  would  be  found  too  flat  if  used  to  drive 
a  pinion  of  10.  Now,  since  the  pitch  diameter  of  the  pinion 
is  to  the  pitch  diameter  of  the  wheel  as  the  number  of  leaves 
in  the  pinion  are  to  the  number  of  teeth  in  the  wheel,  in 
order  to  secure  perfect  teeth:  we  must  adopt  for  the  height 
of  the  addenda  a  certain  proportion  of  the  radius  or  diameter 
of  the  pinion  it  is  to  drive,  this  proportion  depending  on  the 
number  of  leaves  in  the  pinion. 

A  careful  study  of  the  experiments  on  this  subject  with 
models  of  depths  constructed  on  a  large  scale,  shows  that 
the  proportions  given  below  com.e  the  nearest  to  perfection. 

When  the  pinion  has  six  leaves  the  spaces  should  be  twice 
the  width  of  the  leaves  and  the  depth  of  the  space  a  little 
more  than  one-half  the  total  radius  of  the  pinion.  The  ad- 
denda of  the  pinion  should  be  rounded,  and  should  extend 
outside  the  pitch  circle  a  distance  equal  to  about  one-half 
the  width  of  a  leaf.  The  addenda  of  the  wheel  teeth  should 
be  epicycloidal  in  form  and  should  extend  outside  the  pitch 
circle  a  distance  equal  to  five-twelfths  of  the  pitch  radius 
of  the  pinion. 

With  these  proportions,  the  tooth  will  begin  driving  when 
one-half  the  thicknesi-  of  a  leaf  is  in  front  of  the  line  of 
centers,  and  there  will  be  engaging  friction  from  this  point 
until  the  line  of  centers  is  reached. 

This  cannot  be  avoided  with  low-numbered  pinions  with- 
out introducing  a  train  of  evils  more  productive  of  faulty 
action  than  the  one  we  are  trying  to  overcome.  There  will 
be  no  disengaging  friction. 

When  a  pinion  of  seven  is  used,  the  spaces  of  the  pinion 
should  be  twice  the  width  of  the  leaves,  and  the  depth  of  a 
space  about  three-fifths  of  the  total  radius  of  the  pinion. 
The  addenda  of  the  pinion  leaves  should  be  rounded,  and 


214  THE    MODERN    CLOCK. 

should  extend  outside  the  pitch  circle  about  one-half,  the 
width  of  a  leaf.  The  addenda  of  the  wheel  teeth  should  be 
epicycloidal,  and  the  height  of  each  tooth  above  the  pitch 
circle  equal  to  two-fiflhs  of  the  pitch  radius  of  the  pinion. 
'There  is  less  engaging  friction  when  a  pinion  of  seven  is 
used  than  with  one  of  six,  as  the  driving  does  not  begin 
until  two-thirds  of  the  leaf  is  past  the  line  of  centers.  There 
is  no  disengaging  friction. 

With  an  eight-leaf  pinion  the  space  should  be  twice  as 
wide  as  the  leaf,  and  the  depth  of  a  space  about  one-half  the 
total  radius  of  the  pinion.  The  addenda  of  the  pinion  leaves 
should  be  rounded  and  about  one-half  the  width  of  a  leaf 
outside  the  pitch  circle.  The  addenda  of  the  wheel  teeth 
should  be  epicycloidal,  and  the  height  of  each  tooth  above 
the  pitch  circle  equal  to  seven-twentieths  of  the  pitch  radius 
of  the  pinion. 

With  a  pinion  of  eight  there  is  still  less  engaging  friction 
than  with  one  of  seven,  as  three-quarters  of  the  width  of  a 
leaf  is  past  the  line  of  centers  when  the  driving  begins.  As 
there  is  no  disengaging  friction,  a  pinion  of  this  number 
makes  a  very  satisfactory  depth. 

A  pinion  with  nine  leaves  is  sometimes,  though  seldom,, 
used.  It  should  have  the  spaces  twice  the  width  of  the 
leaves,  and  the  depth  of  a  space  one-half  the  total  radius. 
The  addenda  should  be  rounded,  and  its  height  above  the 
pitch  circle  equal  to  one-half  the  width  of  the  leaf.  The 
addenda  of  the  wheel  teeth  should  be  epicycloidal,  and  the 
height  of  each  tooth  above  the  pitch  circle  equal  to  three- 
sevenths  of  the  total  radius  of  the  pinion.  With  this  pinion 
the  driving  begins  very  near  the  line  of  centers,  only  about 
one-fifth  of  the  width  of  a  leaf  being  in  front  of  the  line. 

A  pinion  of  ten  leaves  is  the  lowest  number  with  which 
we  can  entirely  eliminate  engaging  friction,  and  to  do  so  in 
this  case  the  proper  proportions  must  be  rigidly  adhered  to. 
The  spaces  on  the  pinion  must  be  a  little  more  than  twice 
as  w^de  as  a  leaf;   a  leaf  and  space  will  occupy  36°  of  arc; 


THE    MODERN    CLOCK.  215 

of  this  11°  should  be  taken  for  the  leaf  and  25°  for  the 
space.  The  addenda  should  be  rounded  and  should  extend 
about  half  the  width  of  a  leaf  outside  the  pitch  circle.  The 
depth  of  a  space  should  be  equal  to  about  one-half  the  total 
radius.  For  the  wheel,  the  teeth  should  be  equal  in  width 
to  the  spaces,  the  addenda  epicycloidal  in  form,  and  the 
"height  of  each  tooth  above  the  pitch  circle,  equal  to  two- 
fifths  the  pitch  radius  of  the  pinion. 

A  pinion  having  eleven  leaves  would  give  a  better  depth, 
theoretically,  than  one  of  ten,  as  the  leaves  need  not  be  made 
quite  so  thin  to  ensure  its  not  coming  in  action  in  front  of 
the  line  of  centers.  It  is  seldom  seen  in  watch  or  clock 
work,  but  if  needed  the  same  proportions  should  be  used 
as  with  one  of  ten,  except  that  the  leaves  may  be  made  a 
little  thicker  in  proportion  to  the  spaces. 

A  pinion  having  twelve  leaves  is  the  lowest  number  with 
which  we  can  secure  a  theoretically  perfect  action,  without 
sacrificing  the  strength  of  the  leaves  or  the  requisite  freedom 
in  the  depths.  In  this  pinion,  the  leaf  should  be  to  the  space 
as  two  to  three,  that  is,  we  divide  the  arc  of  the  circum- 
ference needed  for  a  leaf  and  space  into  five  equal  parts, 
and  take  two  of  these  parts  for  the  leaf,  and  three  for  the 
space;  depth  of  the  space  should  be  about  one-half  the 
total  radius.  The  addenda  of  the  wheel  teeth  should  be 
epicycloidal,  and  the  height  of  each  tooth  above  the  pitch 
line  equal  to  two-sevenths  the  pitch  radius  of  the  pinion. 

As  the  number  of  leaves  is  increased  up  to  twenty,  the 
width  of  the  space  should  be  decreased,  until  when  this 
number  is  reached  the  space  should  be  one-seventh  wider 
than  the  leaf.  As  these  numbers  are  used  chiefly  for  wind- 
ing wheels  in  watches,  where  considerable  strength  is  re- 
quired, the  bottoms  of  the  spaces  of  both  mobiles  should  be 
rounded. 

Circular  Pitch.  Diametral  Pitch. — In  large  ma- 
chinery it  is  usual  to  take  the  circumference  and  divide  by 
the  number  of  teeth ;   this  is  called  the  circular  pitch,  or  dis- 


2l6  THE    MODERN    CLOCK. 

tance  from  point  to  point  of  the  teeth,  and  is  useful  for  de- 
scribing teeth  to  be  cut  out  as  patterns  for  casting. 

But  for  all  small  wheels  it  is  more  convenient  to  take  the 
diameter  and  divide  by  the  number  of  teeth.  This  is  called 
the  diametral  pitch,  and  when  the  diameter  of  a  wheel  or 
pinion  which  is  intended  to  work  into  it  is  desired,  such 
diameter  bears  the  same  ratio  or  proportion  as  the  number 
required.  Both  diameters  are  for  their  pitch  circles.  As 
the  teeth  of  each  wheel  project  from  the  pitch  circle  and 
enter  into  the  other,  an  addition  of  corresponding  amount 
is  made  to  each  wheel ;  this  is  called  the  addendum.  As  the 
size  of  a  tooth  of  the  wheel  and  of  a  tooth  of  the  pinion  are 
the  same,  the  amount  of  the  addendum  is  equal  for  both  ; 
consequently  the  outside  diameter  of  the  smaller  wheel  or 
pinion  will  be  greater  than  the  arithmetical  proportion  be- 
tween the  pitch  circles.  As  the  diameters  are  measured  pre- 
sumably in  inches  or  parts  of  an  inch,  the  number  of  a 
wheel  of  given  size  is  divided  by  the  diameter,  which  gives 
the  number  of  teeth  to  each  inch  of  diameter,  and  is  called 
the  diametral  pitch.  In  all  newly-designed  machinery  a 
whole  number  is  used  and  the  sizes  of  the  wheels  calculated 
accordingly,  but  when,  as  in  repairing,  a  wheel  of  any  size 
has  any  number  of  teeth,  the  diametral  number  may  have  an 
additional  fraction,  whicli  docs  not  affect  the  principle  but 
gives  a  little  more  trouble  in  calculation.  Take  for  ex- 
ample a  clock  main  wheel  and  center  pinion :  Assuming 
the  wheel  to  be  exactly  three  inches  in  diameter  at  the  pitch 
line,  and  to  have  ninety-six  teeth,  the  result  will  be  96-1-3 
=  ^2,  or  32  teeth  to  each  inch  of  diameter,  and  would  be 
called  ^2  pitch.  A  pinion  of  8  to  gear  with  this  wheel 
would  have  a  diameter  at  the  pitch  line  of  8  of  these  thirty- 
seconds  of  an  inch  or  8-32  of  an  inch.  But  possibly  the 
wheel  might  not  be  of  such  an  easily  manageable  size.  It 
might,  say,  be  3.25  inches,  in  which  case,  96  being  the  num- 
ber of  the  wheel  and  8  of  the  pinion,  the  ratio  is  8-96  or  1-12, 
so  1-12  of  3.25  :=  0.270,  the  pitch  diameter  of  the  pinion. 


THE    MODERN    CLOCK.  217 

These  two  examples  are  given  to  indicate  alternative  meth- 
ods, the  most  convenient  of  which  may  be  used.  After 
arriving  at  the  true  pitch  diameters  the  matter  of  the  adden- 
dum arises,  and  it  is  for  this  that  the  diametral  number  is 
specially  useful,  as  in  every  case  when  figuring  by  this 
system,  whatever  the  number  of  a  wheel  or  pinion,  two  of 
the  pitch  numbers  are  to  be  added.  Thus  with  the  32  pitch, 
the  outside  diameter  of  the  wheel  will  be  3  in.  -f-  2-32,  and 
if  the  pinion  8-32  -}-  2-32  =  10-32.  With  the  other  method 
the  same  exactness  is  more  difficult  of  attainment,  but  for 
practical  purposes  it  will  be  near  enough  if  we  use  2-30  of 
an  inch  for  the  addendum,  when  the  result  will  be  3.25  -f- 
2-30  or  33/4  -4-  2-30  =  31-3  in.  nearly  and  the  pinion  0.270 
-f- 2-30  =  0.270  +  .0666  =  0.3366 ;  or  to  v/ork  by  1-3  of 
an  inch  is  near  enough,  giving  the  outside  diameter  of  the 
pinion  a  small  amount  less  than  the  theoretical,  which  is 
always  advisable  for  pinions  which  are  to  be  driven. 

We  represent  by  Figs.  67  to  71  a  wheel  of  sixty  teeth 
gearing  with  a  pinion  of  six  leaves.  The  wheel,  whose 
pitch  diameter  is  represented  by  the  line  mm  is  the  same  ih 
each  figure.  The  pinion,  which  has  for  its  pitch  diameter 
the  line  kk,  is  in  Fig.  67,  of  a  size  proportioned  to  that  of 
the  wheel,  and  its  center  is  placed  at  the  proper  distance; 
that  is  to  say,  the  two  pitch  diameters  are  tangential. 

In  Fig.  68  the  same  pinion,  of  the  proper  size,  has  its 
center  too  far  off ;  the  depthing  is  too  shallow.  In  Fig.  69 
it  is  too  deep.  Figs.  70  and  71  represent  gearing  in  which 
the  pitch  circles  are  in  contact,  as  the  theory  requires,  but 
the  size  of  the  pinions  is  incorrect.  If  the  wheels  and  pinion 
actuated  each  other  by  simple  contact  the  velocity  of  the 
pinion  with  reference  to  that  of  the  wheel  would  not  be 
absolutely  the  same;  but  the  ratio  of  the  teeth  being  the 
same,  the  same  ratio  of  motion  obtains  in  practice,  and 
there  is  necessarily  bad  w^orking  of  the  teeth  with  the 
leaves. 


2l8  THE    MODERN    CLOCK. 

We  will  observe  what  passes  in  each  of  these  cases,  and 
refer  to  the  suitable  remedies  for  obtaining  a  passable 
depthing  and  a  comparatively  good  rate,  without  the  neces- 
sity of  repairs  at  a  cost  out  of  all  proportion  with  the  value 
of  the  article  repaired. 


^      \  \    J  ^    ^ '         ^ — ^  '^  i'L    A'    >    /    ^"^ 


Fig.  67 

Fig.  6y  represents  gearing  of  which  the  wheel  and  pinion 
are  well  proportioned  and  at  the  proper  distance  from  each 
other.  Its  movement  is  smooth,  but  it  has  little  drop  or 
none  at  all.  By  examining  the  teeth  h,  h',  of  the  wheel,  it 
is  seen  that  they  are  larger  than  the  interval  between  them. 
With  a  cutter  FF,  introduced  between  the  teeth,  they  are 
reduced  at  d,  d',  which  gives  the  necessary  drop  without 
changing  the  functions,  since  the  pitch  circles  mm  and  kk 
have  not  been  modified.  The  drop,  the  play  between  the 
tooth  d'  and  the  leaf  a,  is  sufficiently  increased  for  the  work- 
ing of  the  gearing  with  safety. 

We  have  the  same  pair  in  Fig.  68,  but  here  their  pitch 
circles  do  not  touch ;  the  depthing  is  too  shallow.  The 
drop  is  too  great  and  butting  is  produced  between  the  tooth 
h  and  the  leaf  r,  which  can  be  readily  felt.  The  remedy  is 
in   changing  the   center  distance,   by  closing  the   holes,   if 


THE    MODERN    CLOCK. 


219 


worn,  or  moving  one  nearer  the  other.  But  in  an  ordinary 
clock  this  wheel  may  be  replaced  with  a  larger  one,  whose 
pitch  circle  reaches  to  e.  The  proportions  of  the  pair  are 
modified,  but  not  sufficiently  to  produce  inconvenience. 

It  may  also  answer  to  stretch  the  wheel,  if  it  is  thick 
enough  to  be  sufficiently  increased  in  size.  A  cutte*^  should 
then  be  selected  for  rounding  up  which  will  allow  the  full 


Fig. 


width  to  the  tooth  as  at  p;  but  if  it  is  not  possible  to  en- 
large the  wheel  enough,  a  little  of  the  width  of  the  teeth 
may  be  taken  off,  as  is  seen  at  h,  which  will  diminish  the 
butting  with  the  leaf  r. 

Too  great  depthing.  Fig.  69,  can  generally  be  recognized 
by  the  lack  of  drop.  When  the  teeth  of  the  wheel  are  nar- 
row, the  drop  may  appear  to  be  sufficient.  When  the  train 
is  put  in  action  the  depthing  that  is  too  great  produces 
scratching  or  butting  and  the  'scape  wheel  trembles.  This 
results  from  the  fact  that  the  points  of  the  teeth  of  the 
wheel  touch  the  core  of  the  pinion  and  cause  it  to  butt 
against  the  leaf  following  the  one  engaged,  as  is  visible  at 
r  in  Fig.  69.  It  should  be  noticed  that  in  this  figure  the 
pitch  circles  mm  and  kk  overlap  each  other,  instead  of  being 
tangential. 


220 


THE    MODERN    CLOCK 


Fiir.  CO 


nc 


^^ 


Fig.  TO 


THE    MODERN    CLOCK.  221 

To  correct  this  gearing,  the  cutter  should  act  only  on  the 
addenda  of  the  teeth  of  the  wheel,  so  as  to  diminish  them 
and  bring  the  pitch  circle  mm  to  n.  The  dots  in  the  teeth 
d,  d',  show  the  corrected  gearing.  It  is  seen  that  there  will 
be,  after  this  change,  the  necessary  drop,  and  that  the  end 
of  the  tooth  d'  will  not  touch  the  leaf  r. 

In  the  two  preceding  cases  we  have  considered  wheels 
and  pinions  of  accurate  proportion,  and  the  defects  of  the 
gearing  proceeding  from  the  wrong  center  distances.  We 
will  not  speak  of  the  gearing  in  which  the  pinion  is  too 
small.  The  only  theoretic  remedy  in  this  case,  as  in  that 
of  too  large  a  pinion,  is  to  replace  the  defective  piece;  but 
in  practice,  when  time  and  money  are  to  be  saved,  advan- 
tage must  be  taken,  one  w^ay  or  another,  of  what  is  in 
existence. 

The  buzzing  produced  when  the  train  runs  in  a  gearing 
with  top  small  a  pinion  proceeds  from  the  fact  that  each 
tooth  has  a  slight  drop  before  engaging  with  the  corre- 
sponding leaf.  If  we  examine  Fig.  70,  it  will  be  easy  to 
see  how  this  drop  is  produced.  The  wheel  revolving  in  the 
direction  indicated  by  the  arrow,  it  can  be  seen  that  when 
the  tooth  h  leaves  the  leaf  r,  the  following  tooth,  p,  does  not 
engage  with  the  corresponding  leaf,  s ;  this  tooth  will  there- 
fore have  some  drop  before  reaching  the  leaf.  A  friction 
may  even  be  produced  at  the  end  or  addendum  of  the  tooth 
p  against  the  following  leaf  v. 

To  obtain  a  fair  depthing  without  replacing  the  pinion, 
the  wheels  can  be  passed  to  the  rounding  up  machine,  hav- 
ing a  cutter  which  will  take  off  only  the  points  of  the  teeth, 
as  is  indicated  in  the  figure ;  the  result  may  be  observed  by 
the  dotted  lines.  The  tooth  h  being  shorter,  it  will  leave 
the  leaf  r  of  the  pinion  when  the  latter  is  in  the  dotted 
position;  that  is  to  say,  a  little  sooner.  At  this  moment 
the  tooth  p  is  in  contact  with  the  leaf  s,  and  there  is  no  risk 
of  friction  against  the  leaf  v.  Care  must  be  taken  to  touch 
only  the  addendum  of  the  tooth  so  as  not  to  weaken  the 


222 


THE    MODERN    CLOCK. 


teeth.  The  circumference  i  will  be  that  of  a  pinion  of  ac- 
curate size,  and  if  the  pinion  is  replaced,  it  will  be  necessary 
to  diminish  the  wheel  so  that  its  pitch  circle  shall  be  tan- 
gential with  i. 

-  With  too  small  a  pinion  a  passable  gearing  can  generally 
be  produced.  In  any  case  stoppage  can  be  prevented.  This 
is  not  so  easy  when  the  pinion  is  too  large.     In  Fig.  71,  the 


Fig.  71 

pinion  has  as  its  pitch  circle  the  line  k,  inscead  of  i,  which 
would  be  nearer  the  size  with  reference  to  that  of  the  wheel. 
This  is  purposely  drawn  a  little  small  for  clearness  of  illus- 
tration. The  essential  defect  of  such  a  gearing  can  be  seen ; 
the  butting  produced  between  the  tooth  p  and  the  leaf  s  will 
cause  stoppage.  How  shall  this  defect  be  corrected  without 
replacing  the  pinion? 

To  remedy  the  butting  as  far  as  possible,  some  watch- 
makers slope  the  teeth  of  the  wheel  by  decentering  the  cut- 
ter on  the  rounding-up  machine.  At  FF  the  cutter  is  seen 
working  between  the  teeth  d  and  d'.  It  is  evident  that 
when  the  wheel  becomes  smaller  it  is  necessary  to  stretch  it 
out,  and  to  make  use  of  the  cutter  afterwards.     However, 


THE    MODERN    CLOCK. 


223 


the  most  rational  method  is  to  leave  the  teeth  straight,  and 
to  give  them  the  slenderest  form  possible,  after  having  en- 
larged the  wheel  or  having  replaced  it  with  another.  The 
motive  force  of  the  wheel  being  sufficiently  weak,  the  size 
of  the  teeth  may  be  reduced  without  fear.  The  essential 
thing  is  to  suppress  the  butting.  Success  will  be  the  easiest 
when  the  teeth  are  thinner. 

In  conclusion,  we  recommend  verification  of  all  sus- 
pected gearings  by  the  depthing  tool,  which  is  easier  and 
surer  than  by  the  clock  itself.  One  can  see  better  by  the 
tool  the  working  of  the  teeth  with  the  leaves,  and  can  form 
a  better  idea  of  the  defect  to  be  corrected.  With  the  aid  of 
the  illustrations  that  have  been  given  it  can  be  readily 
noticed  whether  the  depthing  is  too  deep  or  too  shallow,  or 
the  pinion  too  large  or  too  small. 

The  defects  mentioned  are  of  less  consequence  in  a  pinion 
of  seven  leaves,  and  they  are  corrected  more  readily.  With 
pinions  of  higher  numbers  the  depthings  will  be  smoother, 
provided  sufficient  care  has  been  taken  in  the  choice  of  the 
rounding-up  cutters. 

Rounding-Up  Wheels. — It  is  frequently  observed  that 
young  watchmakers,  and  (regretfully  be  it  said)  some  of 
the  older  and  more  experienced  ones,  are  rather  careless 
when  fitting  wheels  on  pinions.  In  many  cases  the  wheel  is 
simply  held  in  the  fingers  and  the  hole  opened  with  a  broach, 
and  in  doing  this  no  special  care  is  taken  to  keep  the  fiole 
truly  central  and  of  correct  size  to  fit  the  pinion  snugly,  and 
should  it  be  opened  a  little  too  large  it  is  riveted  on  the 
pinion  whether  concentric  or  not.  Many  suppose  the  round- 
ing-up tool  will  then  make  it  correct  without  further  trouble 
and  without  sufficient  thought  of  the  irregularities  ensuing 
when  using  the  tool. 

To  make  the  subject  perfectly  clear  the  subjoined  but 
rather  exaggerated  sketch  is  shown,  Fig.  ^2.  Of  course,  it 
is  seldom  required  to  round-up  a  wheel  of  twelve  teeth,  and 


224  "^^^    MODERN    CLOCK. 

the  eccentricity  of  the  wheel  would  be  hardly  as  great  as 
shown;  nevertheless,  assuming  such  a  case  to  occur  the 
drawing  will  exactly  indicate  the  imperfections  arising  from 
the  use  of  a  rounding-up  tool. 

'  Presuming  from  the  drawing  that  the  wheel,  as  shown  by 
dotted  lines,  had  originally  been  cut  with  its  center  at  m, 
but  through  careless  fitting  had  been  placed  on  the  pinion  at 
o,  and  consequently  is  very  much  out  of  round  when  tested 
in  the  calipers,  and  to  correct  this  defect  it  is  put  in  the 

7 


6 


il '-'': 


rounding-up  tool.  The  cutter  commences  to  remove  the 
metal  from  tooth  y,  it  being  the  highest,  next  the  neighbor- 
mg  teeth  6  and  8,  then  5  and  9,  and  so  on  until  tooth  i  comes 
in  contact  with  the  cutter.  The  wheel  is  now  round.  But 
how  about  the  size  of  the  teeth  and  the  pitch  ?  The  result  of 
the  action  of  the  cutter  is  shown  by  the  sectionally  lined 
wheel.  J\Iany  will  ask  how  such  a  result  is  possible,  as  the 
cutter  has  acted  equally  upon  all  the  teeth.  Nevertheless,  a 
little  study  of  the  action  of  the  rounding-up  cutter  will  soon 
make  it  plain  why  such  faults  arise.  Naturally  the  spaces 
between  the  teeth  through  the  action  of  the  cutter  will  be 
equal,  but  as  the  cutter  is  compelled  to  remove  considerable 


THE    MODERN    CLOCK.  22^ 

metal  from  the  point  of  greatest  eccentricity,  i.  e.,  at  tooth  7 
and  the  adjoining  teeth,  to  make  the  wheel  round,  and  the 
pitch  circle  being  smaller  the  teeth  become  thinner,  as  the 
space  between  the  teeth  remains  the  same.  At  tooth  i  no 
metal  was  removed,  consequently  it  remains  in  its  original 
condition.  The  pitch  from  each  side  of  tooth  i  becomes  less 
and  less  to  tooth  7,  and  the  teeth  thinner,  and  the  thickest 
tooth  is  always  found  opposite  the  thinnest. 

In  the  case  of  a  wheel  having  a  large  number  of  teeth  and 
the  eccentricity  of  which  is  small,  such  faults  as  described 
cannot  be  readilv  seen,  from  the  fact  that  there  are  many 
teeth  and  the  slight  change  in  each  is  so  gradual  that  the 
only  way  to  detect  the  difference  is  by  comparing  opposite 
teeth.  And  this  eccentricity  becomes  a  serious  matter  when 
there  are  but  few  teeth,  as  before  explained,  especially  when 
reducing  an  escape  wheel.  The  only  proper  course  to 
pursue  is  to  cement  the  wheel  on  a  chuck,  by  putting  it  in  a 
step  chuck  or  in  any  suitable  manner  so  that  it  can  be  trued 
by  its  periphery  and  then  opening  the  hole  truly.  This 
method  is  followed  by  all  expert  workmen. 

A  closer  examination  of  the  drawing  teaches  us  that  an 
eccentric  wheel  with  pointed  teeth — as  cycloidal  teeth  are 
mostly  left  in  this  condition  when  placed  in  the  rounding-up 
tool,  will  not  be  made  round,  because  when  the  cutter  has 
just  pointed  the  correct  tooth  (tooth  No.  i  in  the  drawing) 
it  will  necessarily  shorten  the  thinner  teeth,  Nos.  6,  7,  8,  i.  e., 
the  pitch  circle  v/ill  be  smaller  in  diameter.  We  can,  there- 
fore, understand  why  the  rounding-up  tool  does  not  make 
the  wheel  round. 

As  we  have  before  observed,  when  rounding-up  an  eccen- 
trically riveted  wheel,  the  thickest  tooth  is  always  opposite 
the  thinnest,  but  with  a  wheel  which  has  been  stretched  the 
case  is  somewhat  different.  Most  wheels  when  stretched 
become  angular,  as  the  arcs  between  the  arms  move  outward 
in  a  greater  or  less  degree,  which  can  be  improved  to  some 
extent  by  carefully  hammering  the  wheel  near  the  arms,  but 


226 


THE    MODERN    CLOCK. 


some  inequalities  will  still  remain.  In  stretching  a  wheel 
with  five  arms  we  therefore  have  five  high  and  as  many  de- 
pressed parts  on  its  periphery.  If  this  wheel  is  now  rounded- 
up  the  five  high  parts  will  contain  thinner  teeth  than  the 
depressed  portions.  Notwithstanding  that  the  stretching  of 
wheels,  though  objectionable,  is  often  unavoidable  on  ac- 
count of  the  low  price  of  repairs,  it  certainly  ought  not  to  be 
overdone.  Before  placing  the  wheel  in  the  rounding-up  tool 
it  should  be  tested  in  the  calipers  and  the  low  places  care- 
fully stretched  so  that  the  wheel  is  as  nearly  round  as  can  be 
made  before  the  cutter  acts  upon  it. 

It  is  hardly  necessary  to  mention  that  the  rounding-up  tool 
will  not  equalize  the  teeth  of  a  badly  cut  wheel,  and  further 
should  there  be  a  burr  on  some  of  the  teeth  which  has  not 
been  removed,  the  action  of  the  guide  and  cutter  in  entering 
a  space  will  not  move  the  wheel  the  same  distance  at  each 
tooth,  thus  producing  thick  and  thin  teeth.  From  what  has 
been  said  it  would  be  wrong  to  conclude  that  the  rounding- 
up  tool  is  a  useless  one ;  on  the  contrary,  it  is  a  practical  and 
indispensable  tool,  but  to  render  good  service  it  must  be  cor- 
rectly used. 

In  the  use  of  the  rounding-up  tool  the  following  rules  are 
to  be  observed : 

1.  In  a  new  wheel  enlarge  the  hole  after  truing  the  wheel 
from  the  outside  and  stake  it  concentrically  on  its  pinion. 

2.  In  a  rivetted  but  untrue  wheel,  stretch  the  deeper  por- 
tions until  it  runs  true,  then  reduce  it  in  the  rounding-up 
tool.  The  better  method  is  to  remove  the  wheel  from  its 
pinion,  bush  the  hole,  open  concentrically  with  the  outside 
and  rivet,  as  previously  mentioned  in  a  preceding  paragraph. 
But  if  the  old  riveting  cannot  be  turned  so  that  it  can  be  used 
again  it  is  best  to  turn  it  entirely  away,  making  the  pinion 
shaft  conical  towards  the  pivot,  and  after  having  bushed  the 
wheel,  drill  a  hole  the  proper  size  and  drive  it  on  the  pinion. 
The  wheel  will  be  then  just  as  secure  as  when  rivetted,  as 
in  doing  the  latter  the  wheel  is  often  distorted.    With  a  very 


THE    MODERN    CLOCK.  227 

thin  wheel  allow  the  bush  to  project  somewhat,  so  that  it 
has  a  secure  hold  on  the  pinion  shaft  and  cannot  work 
loose. 

3.  Should  there  be  a  feather  edge  on  the  teeth,  this 
should  be  removed  with  a  scratch  brush  before  rounding  it 
up,  but  if  for  some  reason  this  cannot  well  be  done,  then 
place  the  wheel  upon  the  rest  with  the  feather  edge  nearest 
the  latter  so  that  the  cutter  does  not  come  immediately  in 
contact  with  it.  If  the  feather  edge  is  only  on  one  side  of 
the  tooth — which  is  often  the  case — place  the  wheel  in  the 
tool  so  that  the  guide  will  turn  it  from  the  opposite  side  of 
the  tooth ;  the  guide  will  now  move  the  wheel  the  correct  dis- 
tance for  the  cutter  to  act  uniformly.  Of  course,  in  every 
case  the  guide,  cutter  and  wheel,  .must  be  in  correct  position 
to  ensure  good  work. 

4.  To  obtain  a  smooth  surface  on  the  face  of  the  teeth 
a  high  cutter  speed  is  required,  and  for  this  reason  it  is  ad- 
vantageous to  drive  the  cutter  spindle  by  a  foot  wheel. 

Making  Single  Pinions. — There  are  two  ways  of  mak- 
ing clock  pinions ;  one  is  to  take  a  solid  piece  of  steel  of  the 
length  and  diameter  needed  and  turn  away  the  surplus  ma- 
terial to  leave  the  arbor  and  the  pinion  head  of  suitable  di- 
mensions ;  the  other  way  is  to  make  the  head  and  the  arbor 
of  separate  pieces;  the  head  drilled  and  fixed  on  the  arbor 
by  friction.  The  latter  plan  saves  a  lot  of  work,  and  the  cut- 
ting of  the  teeth  may  be  easier.  One  method  is  as  good  as 
the  other,  as  the  force  on  the  train  is  very  slight  and  the 
pinion  head  may  be  driven  so  tightly  on  the  arbor  as  to  be 
perfectly  safe  without  any  other  fastening,  provided  the 
arbor  is  given  a  very  small  taper,  .001  inch  in  four  inches. 
The  steel  for  the  arbor  may  be  chosen  of  such  a  size  as  to  re- 
quire very  little  turning,  and  hardened  and  tempered  to  a 
full  or  pale  blue  before  commencing  turning  it,  but  the  piece 
intended  for  the  pinion  head  must  be  thoroughly  annealed, 
or  it  may  be  found  impossible  to  cut  the  teeth  without  de- 


228  THE    MODERN    CLOCK. 

stroying  a  cutter,  which,  being  valuable,  is  worth  taking 
care  of. 

Pinions  for  ordinary  work  are  not  hardened;  as  they  are 
left  soft  by  the  manufacturers  it  would  be  nonsense  for  the 
repairer  to  put  in  one  hardened  pinion  in  a  clock  where  all 
the  others  were  soft.  Pinions  on  fine  work  are  hardened. 
Turning  is  done  between  centers  to  insure  truth. 

Before  commencing  work  on  the  pinion  blanks  it  is  ad- 
visable to  try  the  cutters  on  brass  rod,  turned  to  the  exact 
size,  and  if  the  rod  is  soft  enough  it  will  be  found  that  the 
cutter  will  make  the  spaces  before  it  is  hardened,  which  is 
a  very  important  advantage,  admitting  of  correction  in  the 
form  of  the  cutter  if  required ;  only  two  or  three  teeth  need 
be  cut  in  the  brass  to  enable  one  to  see  if  they  are  suitable, 
and  if  foimd  so,  or  after  an  alteration  of  the  cutter,  the  en- 
tire number  may  be  cut  round  and  the  brass  pinion  made  use 
of  for  testing  its  accuracy  as  to  size  and  shape  by  laying  the 
wheel  along  with  it  on  a  flat  plate,  having  studs  placed  at 
the  proper  center  distance.  By  this  means  the  utmost  re- 
finement may  be  made  in  the  diameter  of  the  brass  pinion, 
which  will  then  serve  as  a  gauge  for  the  diameter  of  the 
steel  pinions,  it  being  recollected,  as  mentioned  in  a  previous 
paragraph,  that  a  slight  variation  in  the  diameter  of  a  pinion 
may  be  made  to  counterbalance  a  slight  deviation  from 
mathematical  accuracy  in  the  form  of  the  wheel-teeth,  such 
as  is  liable  to  occur  owing  to  the  smallness  of  the  teeth  mak- 
ing it  impracticable  to  actually  draw  the  true  curves,  the 
only  way  of  getting  them  being  to  draw  them  to  an  enlarged 
scale  on  paper,  and  copy  them  on  the  cutter  as  truly  as  pos- 
sible by  the  eye. 

Supposing  the  cutter  has  been  properly  shaped,  hardened 
and  completed  and  the  steel  pinion  heads  all  turned  to  the 
diameter  of  the  brass  gauge,  the  cutting  may  be  proceeded 
with  without  fear  of  spoiling,  or  further  loss  of  time  which 
might  be  spent  in  cutting  the  long  pinion  leaves;  and  even 
what  is  of  more  importance  in  work  which  does  not  allow  of 


THE    MODEllN    CLOCK.  229 

any  imperfection,  removing  the  temptation,  which  might  be 
strong,  to  let  a  pinion  go,  knowing  it  to  be  less  perfect  than 
it  should  be. 

Assuming  the  pinion  teeth  to  be  satisfactorily  cut,  the  next 
operation  will  be  hardening  and  tempering.  A  good  way  of 
doing  this  is  to  enclose  one  at  a  time  in  a  piece  of  gas  pipe, 
filling  up  the  space  around  the  pinion  with  something  to 
keep  the  air  off  the  work  and  prevent  any  of  the  products  of 
combustion  attacking  the  steel  and  so  injuring  the  surface. 
Common  soap  alone  answers  the  purpose  very  well,  or  it 
may  have  powdered  charcoal  mixed  with  it;  also  the  addi- 
tion of  common  salt  helps  to  keep  the  steel  clean  and  white. 
The  heating  should  be  slow,  giving  time  for  the  pinion  and 
the  outside  of  the  tube  to  both  acquire  the  same  heat.  Over- 
heating should  be  carefully  avoided,  or  there  w^ill  be  scaling 
of  the  surfaces,  injurious  to  the  steel,  and  requiring  time  and 
labor  to  polish  off.  There  is  no  better  way  of  hardening 
than  by  dipping  the  pipe  with  the  pinion  enclosed  in  plain 
cold  water,  or  if  the  pinion  should  drop  out  of  the  tube  into 
the  water  it  will  do  all  the  same.  To  be  sure  the  hardening 
is  satisfactory  it  will  be  as  well  not  to  trust  to  the  clean  white 
color  likely  to  result  from  this  treatment,  but  try  both  ends 
and  the  center  with  a  file.  After  all  this  has  been  success- 
fully accomplished  the  pinions  will  require  tempering,  the 
long  arbors  straightening,  and  the  teeth  polishmg. 

The  drilled  pinion  heads,  if  hardened  at  all  by  the  method 
last  mentioned,  will,  on  account  of  their  short  lengths,  be 
equally  hardened  all  over,  but  if  the  pinion  and  arbor  should 
be  all  in  one  piece  care  will  be  needed  to  ensure  equal  heat- 
ing all  over,  or  one  part  may  be  burnt  and  another  soft. 
Also,  to  guard  against  bending  the  long  arbors,  the  packing 
in  the  tube  will  need  to  be  carefully  done,  so  as  to  produce 
equal  pressure  all  over ;  otherwise,  while  the  steel  is  red  hot, 
and  consequently  soft  enough  to  bend,  even  by  its  own 
weight,  it  may  get  distorted  before  dropping  in  the  water.  A 
long  thin  rod  like  this  almost  invariably  bends  if  heated  on 


230  THE    MODERN    CLOCK. 

an  open  fire  unless  equally  supported  all  along;  if  hardened 
so,  a  little  tin  tray  may  be  bent  up,  filled  with  powdered 
charcoal,  and  the  pinion  bedded  evenly  in  it.  Either  this  way 
or  with  a  tube  the  long  arbor  may  get  bent  before  being 
quenched;  but  if  the  arbor,  though  kept  straight  up  to  this 
point,  should  happen  to  be  dropped  sideways  into  the  water 
the  side  cooled  first  would  contract  most.  To  avoid  this, 
the  arbor  should  be  dropped  endways,  as  vertically  as  pos- 
sible. • 

Tempering  the  Pinions. — For  common  cheap  work  the 
usual  and  quickest  way  is  what  is  called  "blazing  off."  That 
is  done  either  by  dipping  each  piece  singly  in  thick  oil  and 
setting  the  oil  on  fire,  allowing  it  to  burn  away,  or  placing 
a  number  of  pieces  in  a  suitably  sized  pan,  covering  with 
oil,  and  burning  it.  The  result  is  the  same  either  way,  the 
method  being  simply  a  matter  of  convenience  regulated 
by  the  number  of  pieces  to  be  tempered  at  one  time.  As 
the  result  of  blazing  off  is  to  some  extent  uncertain,  and 
the  pinions  apt  to  be  too  soft,  it  will  be  advisable  to  ndopt 
the  process  of  bluing,  by  which  the  temper  desired  may  be 
produced  with  more  accuracy.  The  first  thing  to  do  will 
be  to  clean  the  suriace  of  the  arbor  all  along  on  one  side ; 
the  pinion  head  may  be  left  alone.  As  the  pinion  head 
would  get  overheated  before  the  arbor  had  reached  the  blue 
color,  if  the  piece  were  simply  placed  on  a  bluing  pan  or 
a  lump  of  hot  iron,  it  will  be  necessary  to  provide  a  layer 
of  som€  soft  substance  to  bed  the  pinion  on ;  iron,  steel  or 
brass  filings  answer  well  because  the  heat  is  soon  uniformly 
distributed  through  the  mass,  and  by  judiciously  moving  the 
lamp  an  equable  temper  may  be  got  all  along,  as  deter- 
mined by  the  color.  There  is  another  and  very  sure  way 
of  getting  a  uniform  temper,  in  using  which  there  is  no 
need  to  polish  the  arbors.  The  heat  of  lead  at  the  point  of 
fusion  happens  to  be  just  about  the  same  as  that  required 
for  the  tempering  of  this  work;  so  if  a  ladle  full  of  lead 


THE    MODERN    CLOCKc  231 

is  available  each  pinion  may  be  buried  in  it  for  a  few  sec- 
onds, holding  it  down  beneath  the  molten  surface  with  hot 
pHers.  The  temper  suitable  is  indicated  by  a  pale  blue,  a 
little  softer  than  for  springs,  and  a  piece  of  poHshed  steel 
set  floating  on  the  lead  will  indicate  whether  the  heat  is 
suitable;  if  found  too  great  some  tin  may  be  added,  which 
will  cause  the  metal  to  melt  at  a  lower  temperature.  Over- 
heating the  metal  must  be  avoided:  it  should  go  no  higher 
than  the  bare  melting  point. 

Straightening  Bent  Arbors. — When. all  care  has  been 
taken  in  the  hardening,  the  long  pieces  of  wire  are  still 
apt  to  become  bent  more  or  less,  and  this  is  especially  the 
case  with  solid  pinions ;  so  before  proceeding  further  the 
pieces  must  be  got  true,  or  as  nearly  so  as  possible,  and  it 
will  be  found  impracticable  to  do  this  by  simple  bending 
when  the  steel  is  tempered.  If  the  piece  is  placed  between 
centers  in  the  lathe  and  rotated  slowly,  the  hollow  side  will 
be  found;  this  side  must  be  kept  uppermost  while  the  steel 
is  held  on  a  smooth  anvil,  and  the  pene,  or  chisel-shaped, 
end  of  a  small  hammer  applied  crossways  with  gentle 
blows,  stepping  evenly  along  so  that  each  portion  of  the 
steel  is  struck  all  along  the  part  which  is  hollow ;  this  will 
stretch  the  hollow  side,  and,  by  careful  working,  trying  the 
truth  from  time  to  time,  the  piece  can  be  got  as  true  as  may 
be  wished,  and  probably  keep  so  during  the  subsequent  turn- 
ing and  finishing,  though  it  is  advisable  to  keep  watch  on  it, 
and  if  it  shows  any  tendency  to  spring  out  of  truth  again, 
repeat  the  striking  process,  which  should  always  be  done 
gently  and  in  such  a  way  as  to  show  no  hammer  marks. 
Having  got  the  pieces  suf^ciently  true  in  this  way,  each 
arbor  may  have  a  collet  of  suitable  size  driven  on  to  it  for 
permanency,  and  as  the  collets  will  probably  be  a  little  out 
of  truth  they  may  have  a  finishing  cut  taken  all  over  them 
and  receive  a  final  polish. 


232  THE    MODERN    CLOCK. 

Polishing. — To  polish  the  steel  arbors  after  turning,  a 
flat  metal  polisher,  iron  or  steel,  is  used;  this  with  emery 
or  oilstone  dust  and  oil  produces  a  true  surface,  with  a 
sharp  corner  at  the  shoulder;  the  polisher  will  require  fre- 
quent filing  on  the  flat  and  the  edge  to  keep  it  in  shape 
with  a  sharp  corner,  and  a  grain  crossing  like  the  cuts  on 
a  file  to  hold  the  grinding  material.  The  polishing  of  ar- 
bors is  not  done  with  the  object  of  making  them  shine,  but 
to  get  them  smooth  and  true,  so  there  is  no  need  of  using 
any  finer  stuff  than  emery  or  oilstone  dust. 

An  old  way  to  polish  the  leaves  was  to  use  a  simple 
metal  polisher  of  a  suitable  thickness,  placing  the  pinion  on 
a  cork  or  piece  of  wood,  or  even  holding  it  in  the  fingers ; 
working  away  at  a  tooth  at  a  time  until  a  good  enough  pol- 
ish was  obtained;  but  this  method,  while  being  satisfactory 
as  to  results,  was  also  tedious  and  very  slow.  4t  was  in 
some  cases  assisted  by  having  guide  pinions  fitted  tight  on 
one  or  both  ends  of  the  arbors  to  prevent  rounding  of  the 
teeth,  the  polisher  resting  in  the  guide  and  the  tooth  to  be 
polished.  On  the  American  lathes  an  accessory  is  provided 
called  a  "wig  wag."  This  is  a  rod  fastened  at  one  end  to  a 
pulley  by  a  crank  pin  near  its  circumference ;  the  pulley 
being  rotated  by  a  belt  from  the  counter  shaft  pulleys 
causes  the  rod  to  move  rapidly  backwards  and  forwards. 
On  the  other  end  of  the  rod  a  long  narrow  piece  of  lead 
or  tin  is  fixed,  the  pinion  being  fitted  by  its  centres  into  a 
simple  frame  held  in  the  slide  rest  so  that  it  can  be  rotated 
tooth  by  tooth;  the  lead  soon  gets  cut  to  the  form  of  the 
teeth,  and  the  polishing  is  quickly  effected.  Another  way 
is  to  take  soft  pine  or  basswood,  shape  it  roughly  to  about 
the  form  of  space  between  two  teeth  and  use  it  as  a  file, 
with  emery  and  oil  or  oilstone  dust.  The  wood  is  soon  cut 
to  the  exact  shape  of  the  teeth,  and  then  makes  a  quick  and 
perfect  job.  The  pinion  is  held  in  the  jaws  of  the  vise  and 
the  wooden  polisher  used  as  a  file  with  both  hands. 


THE    MODERN    CLOCK. 


233 


Where  there  is  much  polishing  to  do  a  simple  tool, 
which  a  workman  can  form  for  himself,  produces  a  result 
which  is  all  that  can  be  desired.  It  consists  of  an  arbor 
to  work  between  the  lathe  centres,  or  a  screw  chuck  for 
wood,  with  a  round  block  of  soft  wood,  of  a  good  diameter, 
fixed  on  it,  and  turned  true  and  square  across ;  this  will  get 
a  spiral  groove  cut  in  it  by  the  corners  of  the  pinion  leaves. 
The  pinion  is  set  between  centres  in  a  holder  in  the  slide 
rest,  with  the  holder  set  at  a  slight  angle,  so  that,  instead  of 
circular  grooves  being  cut  in  the  wood  a  screw  will  be 
formed,  the  angle  being  found  by  trial.  On  the  wood  block 
being  rotated  and  supplied  with  fine  emery  the  pinion  will 
be  found  to  rotate,  and,  being  drawn  backwards  and  for- 
wards by  the  slide  rest,  can  be  polished  straight,  while  the 
circular  action  of  the  polisher  will  cause  the  sides  of  the 
pinion  leaves  to  be  made  quite  smooth  and  entirely  free 
from  ridges. 

If  it  should  be  desired  to  face  the  pinions,  like  watch 
pinions,  it  may  be  done  in  the  same  way,  by  cutting  hollows 
so  as  to  leave  only  a  fine  ring  round  the  bottoms  of  the 
teeth,  and  using  a  hollow  polisher  with  a  flat  end  held  in  the 
fingers  while  the  pinion  is  rotating.  A  common  cartridge 
shell  with  a  hole  larger  than  the  arbor  drilled  in  the  center 
of  the  head  makes  a  fine  polisher  for  square  facing  on  the 
ends  of  pinions,  while  a  stick  of  soft  wood  will  readily  adapt 
itself  to  moulded  ends. 

The  pinion  heads  being  finished  and  got  quite  true,  the 
arbors  may  be  turned  true  and  polished.  It  is  not  advisable 
to  turn  the  arbors  small ;  they  will  be  better  left  thick  so  as 
to  be  stiff  and  solid,  as  the  weight  so  near  the  center  is  of 
no  importance,  the  velocity  on  the  small  circumference  in 
starting  and  stopping  being  also  inappreciable.  The  thick- 
ness of  the  arbors  when  the  pinion  heads  are  drilled  is  de- 
termined by  the  necessity  of  having  sufficient  body  inside 
the  bottoms  of  the  teeth ;  but  when  solid  they  may  with  ad- 
vantage be  left  thicker;  however,  there  is  no  absolute  size. 


234 


THE    MODERN    CLOCK. 


The  ends  on  which  the  collets  for  holding  the  wheels  are  to 
be  fixed  may  be  turned  to  the  same  taper  as  the  broach 
which  will  be  used  for  opening  the  collet  holes,  while  the 
other  ends  may  be  straight. 

'None  of  the  wheels  in  a  fine  clock  should  be  riveted 
to  the  pinion  heads ;  even  the  center  wheel,  which  goes  quite 
up  to  the  pinion  head,  is  generally  fixed  on  a  collet.  The 
collets  are  made  from  brass  cut  off  a  round  rod,  the  outside 
diameters  being  just  inside  the  edges  of  the  wheel  hubs, 
and  a  shoulder  turned  to  fit  accurately  into  the  center  hole 
of  each  wheel.  These  collets  should  first  have  their  holes 
broached  to  fit  their  arbors,  allowing  a  little  for  driving  on, 
as  they  may  be  made  tight  enough  in  this  way  without  sol- 
dering. Be  careful  to  keep  the  broach  oiled  to  prevent 
sticking  if  you  want  a  smooth  round  hole. 

The  holes  in  the  wheels  being  made,  each  collet  may  be 
turned  to  a  little  over  its  final  size  all  over,  and  then  driven 
on  to  its  place  on  the  pinion,  so  that  a  final  turning  may  be 
made  to  ensure  exact  truth  from  the  arbors'  own  centers. 
When  the  collets  are  thus  finished  in  their  places  .on  the  ar- 
bors, and  the  wheels  fitted  to  them,  if  it  is  a  fine  clock,  such 
as  a  regulator,  a  hole  may  be  drilled  through  each  wheel 
and  its  collet  to  take  a  screw,  the  holes  in  the  collet  tapped, 
the  holes  in  the  wheels  enlarged  to  allow  the  screw  to  pass 
freely  through,  and  a  countersink  made  to  each,  so  that  the 
screws,  when  finished,  may  be  flush  with  the  wheels.  One 
hole  having  been  thus  made  and  the  wheel  fixed  with  a 
screw,  the  other  two  holes  can  be  made  so  as  to  be  true, 
which  would  not  be  so  well  accomplished  if  all  the  holes 
were  attempted  at  once.  The  spacing  of  the  three  screws 
will  be  accurate  enough  if  the  wheel  arms  be  taken  as  a 
guide.  If  all  this  has  been  correctly  done,  the  wheels  will 
go  to  their  places  quite  true,  both  in  the  round  and  the  flat, 
and  may  be  taken  off  for  polishing,  and  replaced  true  with 
certainty,  any  number  of  times. 


THE    MODERN    CLOCK.  235 

The  polishing  of  the  pivots  should  be  as  fine  as  possible ; 
all  should  be  well  burnished,  to  harden  them  and  make  them 
as  smooth  as  possible  if  it  is  a  common  job;  if  a  fine  one 
with  hardened  arbors  the  pivots  may  be  ground  and  pol- 
ished as  in  watch  work ;  if  the  workman  has  a  pivot  polisher 
and  some  thin  square  edged  laps  this  is  a  short  job  and 
should  be  done  before  cutting  off  the  centers  and  rounding 
the  ends  of  the  pivots.  During  all  this  work  the  wheels, 
as  a  matter  of  course,  will  be  removed  from  the  pinions,  and 
m.ay  now  be  again  temporarily  screwed  on,  the  polishing  of 
them  being  deferred  till  the  last,  as  otherwise  they  would 
be  liable  to  be  scratched. 

Lantern  Pinions. — The  lantern  pinion  is  little  under- 
stood outside  of  clock  factories  and  hence  it  is  generally 
underrated,  especially  by  watchmakers  and  those  working 
generally  in  the  finer  branches  of  mechanics.  It  will  never 
be  displaced  in  clock  work,  however,  on  account  of  the  fol- 
lowing specific  advantages : 

I.  It  offers  the  greatest  possible  freedom  from  stoppage 
owing  to  dirt  getting  into  the  pinions,  as  if  a  piece  large 
enough  to  jam  and  stop  a  clock  with  cut  pinions,  gets  into 
the  lantern  pinion,  it  will  either  fall  through  at  once  or  be 
pushed  thiough  between  the  rounds  of  the  pinion  by  the 
tooth  of  the  wheel  and  hence  will  not  interfere  with  its 
operation.  It  is  therefore  excellently  adapted  to  run  under 
adverse  circumstances,  such  as  the  majority  of  common 
clocks  are  subjected  to. 

2.  Without  giving  the  reasons  it  is  demonstrable  that  as 
smooth  a  motion  may  be  got  by  a  lantern  pinion  as  by  a 
solid  radial  pinion  of  twice  the  number,  and  that  the  force 
required  to  overcome  the  friction  of  the  lantern  is  therefore 
much  less  than  with  the  other.  It  follows  that  such  pinions 
can  be  used  with  advantage  in  the  construction  of  all  cheap 
and  roughly  constructed  clocks  which  are  daily  turned  out 
in  thousands  to  sell  at  a  low  price. 


236  THE    MODERN    CLOCK. 

3.  We  have  before  pointed  out  the  enormous  advantages 
of  small  savings  per  movement  in  clock  factories  which  are 
turning  out  an  annual  product  of  millions  of  clocks,  and 
without  going  into  details,  it  is  sufficient  to  refer  to  the 
fact  that  where  eight  or  ten  millions  of  clocks  are  to  be 
made  annually  the  difference  in  the  cost  of  keeping  up  the 
drills  and  other  tools  for  lantern  pinions  over  the  cost  of 
similar  work  on  the  cutters  for  solid  pinions  is  sufficient 
to  have  a  marked  influence  upon  the  cost  of  the  goods. 
Then  the  rapidity  with  which  they  can  be  made  and  the 
consequent  smallness  of  the  plant  as  compared  with  that 
which  must  be  provided  for  turning  out  an  equal  number  of 
cut  pinions  is  also  a  factor.  There  are  other  features,  but 
the  above  will  be  sufficient  to  show  that  it  is  unlikely  that 
the  lantern  pinion  will  ever  be  displaced  in  the  majority  of 
common  clocks.  From  seventy-five  to  ninety  per  cent  of 
the  clocks  now  made  have  lantern  pinions. 

The  main  difference  between  lantern  and  cut  pinions 
mechanically  is  that  as  there  is  no  radial  flank  for  the  curve 
of  the  wheel  tooth  to  press  against  in  the  lantern  pinion 
the  driving  is  all  done  on  or  after  the  line  of  centers,  except 
in  the  smaller  numbers,  and  hence  the  engaging  or  butting 
friction  is  entirely  eliminated  when  the  pinion  is  driven, 
as  is  always  the  case  in  clock  work.  Where  the  pinion  is 
the  driver,  however,  this  condition  is  reversed  and  the  driv- 
ing is  all  before  the  line  of  centers,  so  that  it  makes  a  very 
bad  driver  and  this  is  the  reason  why  it  is  never  used  as  a 
driving  pinion.  This,  of  course,  bars  it  from  use  in  a  large 
class  of  machinery. 

The  actual  making  of  lantern  pinions  will  be  found  to 
offer  no  difficulties  to  those  who  possess  a  lathe  with  divid- 
ing arrangements,  a  slide  rest,  and  a  drill  holder  or  pivot 
polisher  to  be  fixed  on  it.  The  pitch  circle,  being  through 
the  centers  of  the  pins,  can  be  got  with  great  accuracy  by 
setting  the  drill  point  first  to  the  center  of  the  lathe,  read- 
ing the  division  on  the  graduated  head  of  the  slide  rest 


THE    MODERN    CLOCK.  237 

screw,  and  moving  the  drill  point  outwards  to  the  exact 
amount  of  the  semi-diameter  of  the  pitch  circle.  This  pre- 
supposes the  slide  rest  screw  being  cut  to  a  definite  standard, 
as  the  inch  or  the  meter,  and  all  measurements  of  wheels' 
and  pinions  being  worked  out  to  the  same  standard,  the 
choice  of  the  standard  being  immaterial.  If  the  slide  rest 
screw  is  not  standardized  the  pitch  circle  may  be  traced 
with  a  graver  and  the  drill  set  to  center  on  the  line  so 
traced. 

The  heads  of  the  pinions  may  be  made  either  of  two 
separate  discs,  each  drilled  separately,  and  carefully  fitted 
on  the  arbor  so  that  the  pins  may  be  exactly  parallel  with 
the  arbor;  or,  of  one  solid  piece  bored  through  the  center, 
turned  down  deep  enough  in  the  middle,  and  the  drill  sent 
right  through  the  pin  holes  for  both  sides  at  one  operation. 
The  former  way  will  be  necessary  when  the  number  of  pins 
is  small,  but  the  latter  is  better  when  the  numbers  are  large 
enough  to  allow  of  considerable  body  in  the  center.  In 
either  case  it  is  advisable  to  drill  only  part  way  through  one 
shroud  and  to  close  the  holes  in  the  other  with  a  thin  brass 
washer  pressed  on  the  arbor  and  turned  up  to  look  like  part 
of  the  shroud  after  the  pins  are  fitted  in  the  holes.  This 
makes  a  much  neater  way  of  closing  the  holes  than  riveting 
and  takes  but  a  moment  where  only  one  or  two  pinions  are 
being  made. 

There  is  no  essential  proportion  for  the  thickness  of  the 
pins  or  rounds.  In  mathematical  investigations  these  are 
always  taken  at  first  as  mere  points  of  no  thickness  at  all; 
then  the  diameters  are  increased  to  w^orkable  proportions, 
and  the  width  of  the  wheel-tooth  correspondingly  reduced 
until  there  is  a  freedom  or  a  little  shake.  If  much  power 
has  to  be  transmitted,  the  pins,  or  ''staves,"  as  they  are 
called  in  large  work,  have  to  be  strong  enough  to  stand  the 
strain,  but,  as  the  strain  in  clockwork  is  very  small,  the  pins 
need  not  be  nearly  as  thick  as  the  breadth  of  a  wheel-tooth. 
In  modern  factory  practice  the  custom  is  to  have  the  diam- 


238  THE    MODERN    CLOCK. 

eter  of  the  rounds  equal  to  the  thickness  of  the  leaf  of  a  cut 
pinion  of  similar  size,  the  measurement  being  taken  at  the 
pitch  circle  of  the  cut  pinion.  As  we  have  already  given 
the  proportions  observed  in  good  practice  on  cut  pinions 
they  need  not  be  repeated  here.  Another  practice  is  to  have 
wheel  teeth  and  spaces  equal ;  when  this  is  done  the  spacing 
of  all  pinions  above  six  leaf  is  to  have  the  rounds  occupy 
three  parts  and  the  space  five  parts. 

In  some  old  church  clocks,  lantern  pinions  were  much 
used,  in  many  cases  with  the  pins  pivoted  and  working 
freely  in  the  ends,  or,  as  they  called  them,  "shrouds,"  but 
this  was  a  mistake,  and  they  are  never  made  so  now.  A 
simple  way  for  clock  repair  work  is  to  get  some  of  the 
tempered  steel  drill  rod  of  exactly  the  thickness  desired, 
hold  one  end  by  a  split  chuck  in  the  lathe,  let  the  other  end 
run  free,  and  polish  with  a  bit  of  fine  emery  paper  clipped 
round  it  with  the  fingers,  when  the  wire  will  be  ready  for 
driving  through  the  pinion  heads,  the  holes  being  made 
small  enough  to  provide  for  the  rounds  being  firmly  held. 
The  drill  may  be  made  of  the  same  wire.  The  shrouds 
may  be  made  either  of  brass  or  steel ;  the  latter  need  not  be 
hardened,  and,  when  the  rounds  are  all  in  place  and  cut  ofif, 
the  ends  may  be  polished  as  desired.  In  the  case  of  a  cen- 
ter wheel,  where  the  pinion  is  close  up  to  the  wheel,  and 
space  cannot  be  spared,  the  collet  on  which  the  wheel  is 
mounted  may  form  one  end  of  the  pinion  head. 

The  Wheel  Teeth. — The  same  principles  of  calculation 
belong  to  these  and  solid-cut  pinions,  the  only  difference 
being  that  the  round  pins  require  wheel  teeth  of  a  different 
shape  from  those  suited  to  pinion  leaves  with  radial  sides. 
Both  are  derived  from  epicycloidal  curves ;  the  curve  used 
for  lantern  pinions  is  derived  from  a  circle  of  the  same  size 
as  the  pitch  circle  of  the  pinion,  while  the  curve  for  wheel 
teeth  to  drive  radial-sided  leaves  is  derived  from  a  circle  of 
half  that  diameter,  so  that  the  wheel  teeth  in  the  former 


THE    MODERN    CLOCK. 


239 


Fig.  73.    Lantern  pinion  showing  pitch  circle. 


Fig.  74.    Generating  epicycloid  curve   for   lantern  pinion  above ;  com- 
pare with  curve  for  cut  pinion  of  same  size  pitch  circle,  page  206. 


240  THE    MODERN    CLOCK. 

are  more  pointed  than  in  the  latter.  There  also  is  a  farther 
difference;  as  was  explained  in  detail  when  treating  of  cut 
pinions,  the  curve  of  the  wheel  tooth  presses  upon  the  radial 
flank  of  the  leaf  inside  its  pitch  circle.  Now  there  is  no 
radial  flank  in  the  lantern  and  the  curve  is  generated  from 
a  circle  of  twice  the  diameter,  so  that  it  is  twice  as  long — 
long  enough  to  interfere — so  it  is  cut  off  (rounded)  just 
beyond  the  useful  portion  of  the  working  curve  of  the  wheel 
tooth. 

Pillars  and  arbors  are  simple  parts,  yet  much  costly  ma- 
chinery is  used  in  making  them.  The  wire  from  which 
they  are  made  is  brought  tothe  factories  in  large  coils,  and 
is  straightened  and  cut  into  lengths  by  machines.  The 
principle  on  which  wire  is  straightened  in  a  machine  is 
exactly  the  same  as. a  slightly  curved  piece  of  wire  is  made 
straight  in  the  lathe  by  holding  the  side  of  a  turning  tool 
between  the  revolving  wire  and  the  lathe  rest,  which  is  an 
operation  most  of  our  readers  must  have  practiced.  The 
rapid  revolution  of  the  wire  against  the  turning  tool  causes 
its  highest  side  to  yield,  till  finally  it  presses  on  the  turning 
tool  equally  all  round,  and  is  consequently  straight.  How- 
ever, in  straightening  wire  by  machines  the  wire  is  not 
made  to  revolve,  but  remains  stationary  while  the  straight- 
ening apparatus  revolves  around  it.  Wire-straightening  ma- 
chines are  usually  made  in  the  form  of  a  hollow  cylinder, 
having  arms  projecting  from  the  inside  towards  the  center. 
The  cylinder  is  open  at  both  ends,  and  the  arms  are  ad- 
justable to  suit  the  different  thicknesses  of  wire.  The  wire 
is  passed  through  the  ends  of  the  cylinder,  and  comes  in 
contact  with  the  arms  inside.  A  rapid  rotary  motion  is 
then  given  to  the  cylinder,  which  straightens  the  wire  in 
the  most  perfect  manner,  as  it  is  drawn  through,  without 
leaving  any  marks  on  it  when  the  machine  is  properly  ad- 
justed. The  long  spiral  lines  that  are  sometimes  seen  on 
the  w^ire  w^ork  of  clocks  is  caused  by  this  w^ant  of  adjust- 
ment; and  they  are  produced  in  the  same  way  as  broad 


THE    MODERN    CLOCK. 


241 


circular  marks  would  be  made  in  soft  iron  wire  if  the  side 
of  the  turning  tool  was  held  too  hard  against  it  when 
straightening  it  in  the  lathe. 

After  the  wire  has  been  straightened  it  is  cut  off  into 
the  required  lengths,  and  this  operation  is  worthy  of  notice. 
If  the  thick  sizes  of  wire  that  are  used  were  to  be  cut  by 
the  aid  of  a  file  or  a  chisel,  the  ends  would  not  be  square, 
and  some  time  and  material  would  be  lost  in  the  operation 


Fig.  75.    A  Slide  Gauge  Lathe. 

of  squaring  them;  and  as  economy  of  material  as  well  as 
economy  of  labor  is  a  feature  in  American  clock  manufac- 
ture, wire  of  all  sizes  is  sheared  or  broken  off  into  lengths, 
by  being  fed  through  round  holes  in  the  shears,  which  act 
the  same  as  when  a  steady  pin  is  broken  when  a  cock  or 
bridge  gets  a  sudden  blow  on  the  side,  or  in  the  same  man- 
ner as  patent  cutting  plyers  work.  The  wire  is  not  bent  in 
the  operation,  and  both  ends  of  it  are  smooth  and  flat.  The 
wire  for  the  pillars  is  then  taken  to  a  machine  to  have  the 
points  made  and  the  shoulders  formed  for  the  frames  to  rest 
against.  This  machine  is  constructed  like  a  machinist's 
bench  lathe,  with  two  headstocks.  There  is  a  live  spindle 
running  in  both  heads.  In  the  ends  of  these  spindles,  that 
point  towards  the  center  of  the  lathe,  cutters  are  fastened, 
and  the  one  is  shaped  so  that  it  will  form  the  end  and  shoul- 


242  THE    MODERN    CLOCK. 

der  of  the  pillar  that  is  to  be  riveted,  while  the  other  is 
shaped  so  as  to  form  the  shoulder  and  point  that  is  to  be 
pinned.  Between  these  two  revolving  cutters  there  is  an 
arrangement,  worked  by  a  screw  in  the  end  of  a  handle,  for 
holding  the  wire  from  which  the  pillar  is  to  be  made,  in  a 
firm  and  suitable  position.  The  cutters  are  then  made  to 
act  simultaneously  on  the  ends  of  the  wire  by  a  lever  acting 
on  the  spindles,  and  the  points  and  shoulders  are  in  this 
way  formed  in  a  very  rapid  manner,  all  of  the  same  length 
and  diameter.  These  machines  are  in  some  points  auto- 
matic. The  pieces  of  wire  are  arranged  in  quantities  in  a 
long  narrow  feed  box  that  inclines  towards  the  lathe,  and 
the  mechanism  for  holding  the  wire  is  so  arranged  that 
when  its  hold  is  loosened  on  the  newly  made  pillar,  the 
pillar  drops  out  into  a  box  beneath,  and  a  fresh  piece  of 
wire  drops  in  and  occupies  its  place. 

In  many  of  the  factories,  some  clocks  are  manufactured 
having  screws  in  place  of  pins  to  keep  the  frames  together, 
and  the  pillars  of  these  clocks  are  made  in  a  different  man- 
ner than  that  we  have  just  described.  The  wire  that  is  used 
is  not  cut  into  short  lengths,  but  a  turret  lathe  with  a  hol- 
low spindle  is  used,  through  which  the  wire  passes,  and  is 
held  by  a  chuck,  when  a  little  more  than  just  the  length 
that  is  necessary  to  make  the  pillar  projects  through  the 
chuck.  The  revolving  turret  head  of  the  lathe  has  cutting 
tools  projecting  from  it  at  several  points.  One  tool  is 
adapted  to  bore  the  hole  for  the  screw,  and  when  it  is  bored 
the  next  tool  taps  the  hole  to  receive  the  screw,  while  an- 
other forms  the  point  and  shoulder ;  and  after  that  end  of 
the  pillar  is  comipleted  another  tool  attached  to  the  slide 
of  the  lathe  forms  the  other  shoulder,  prepares  that  end  for 
riveting,  and  cuts  it  off  at  the  same  time.  One  thousand 
of  these  pillars  are  in  this  manner  made  in  a  day  on  each 
machine.  The  screws  that  screw  into  them  are  made  on 
automatic  screw  machines.  The  latest  improvements  .in  this 
direction  being  to  first  turn  the  blanks  and  then  roll  the 
threads  on  thread  rolling  machines. 


THE    MODERN    CLOCK.  243 

The  pinion  arbors,  after  they  have  been  cut  to  length,  are 
centered  on  one  end  by  a  milling  machine  having  a  conical 
cutter  made  for  the  purpose.  The  collets  for  the  pinion 
heads,  and  the  one  to  fasten  the  wheel  by,  are  punched  out 
of  sheet  brass,  and  a  hole  is  drilled  in  their  centers  a  little 
smaller  than  the  wire ;  and  to  drive  them  on,  in  most  in- 


Fig.  76.    Slide  Gauge  Tools  and  Rack. 

stances,  is  all  that  is  necessary  to  hold  them.  At  one  time 
it  was  the  practice  to  drive  these  collets  by  hand.  One  was 
placed  on  the  point  of  the  arbor,  and  the  point  was  then 
placed  over  a  piece  of  steel,  with  a  series  of  holes  in  it 
of  such  depths  that  the  collets  would  be  in  their  proper 
position  on  the  arbor  when  the  point  was  driven  to  the 
bottom  of  the  hole,  but  this  method  has  now  been  super- 
seded  by    automatic    machinery,    which    will   be   described 


244  '1'^^    MODERN    CLOCK, 

later.  It  is  impossible  to  give  an  intelligible  description  of 
these  machines  without  drawings.  All  we  can  say  at 
present  is  that  they  perform  their  work  in  a  very  rapid  and 
effective  manner,  and  are  in  use  by  all  the  larger  clock  fac- 
tories. 

The  barrels  of  weight  clocks  are  mostly  made  from 
brass  castings,  and  slight  projections  are  raised  on  the  sur- 
face of  their  arbors  by  swedging,  so  as  to  prevent  the 
arbors  from  getting  loose  in  the  barrels  after  repeated  wind- 
ing of  the  clock.  This  swedging  and  all  the  other  opera- 
tions in  making  arbors  used  to  be  done  on  separate  ma- 
chines; but  the  largest  companies  now  use  a  powerful  and 
comprehensive  machine  that  works  automatically,  and 
straightens  any  size  of  wire  necessary  to  be  used  in  a  clock, 
cuts  it  to  the  length,  centers  it,  and  also  swedges  the  pro- 
jections on  the  barrel  arbors,  or  any  of  the  other  arbors 
that  may  be  necessary.  A  roll  of  wire  is  placed  on  a  reel 
at  one  end  of  the  machine,  first  passing  through  a  straight- 
ening apparatus,  and  afterwards  to  that  portion  of  the  ma- 
chine where  the  cutting,  swedging  and  centering  are  exe- 
cuted, and  the  finished  arbors  drop  into  a  box  placed  ready 
to  receive  them.  The  saving  effected  by  the  use  of  this 
machine  is  very  great,  and  in  some  instances  amounts  to  a 
thousand  per  cent  over  the  method  of  straightening,  cutting, 
swedging  and  centering  on  different  machines,  at  different 
operations. 

Boring  the  holes  in  the  arbors  of  the  locking  work,  to 
receive  the  smaller  wires,  and  the  pin  holes  in  the  points 
of  the  pillars,  is  done  by  small  twist  drills,  run  by  small 
vertical  drill  presses.  The  work  is  held  in  adjustable  frames 
under  the  drill,  and  when  more  than  one  hole  has  to  be 
bored  this  frame  is  moved  backward  or  forward  between 
horizontal  slides  to  the  desired  distance,  which  is  regulated 
by  an  adjustable  stop,  so  that  every  hole  in  each  piece  is 
exactly  in  the  same  position.  In  arbors  where  holes  have 
to  be  bored  at  right  angles  to  each  ether,  the  arbor  is  turned 


THE    MODERN    CLOCK. 


245 


round  to  the  desired  position  by  means  of  an  index.  The 
holes  in  the  locking  work  arbors  are  bored  just  the  size 
to  fit  the  wire  that  is  to  go   into  them,   and  these  small 


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Fig.  77.    Automatic  Pinion  Making  Machine  of  the  Davenport  Machine 

Company. 


wires  are  easily  and  rapidly  fastened  in  place  by  holding 
them  in  a  clamp  made  for  the  purpose,  and  riveting  them 
either  with  a  hammer  or  with  a  hammer  and  punch. 


246  THE    MODERN    CLOCK. 

The  Slide  Gauge  Lathe — The  system  of  turnin;^^  with 
the  sUde  gauge  lathe,  formerly  adopted  for  lantern  pinions 
in  the  clock  factories,  would  seem  to  the  watchmaker  of  a 
peculiarly  novel  nature.  The  turning  tools  are  not  held  in 
the  hand,  in  the  manner  generally  practiced,  neither  are 
they  held  in  the  ordinary  sHde  rest,  but  are  used  by  a  com- 
bination of  both  methods,  which  secures  the  steadiness  of 
the  one  plan  and  the  rapidity  of  the  other.  Adjustable 
knees  are  fastened  to  the  head  and  tail  stocks  of  the  lathCj 
Figs.  75  and  76,  which  answer  the  purpose  of  a  rest ;  both 
the  perpendicular  and  horizontal  parts  of  these  knees  being 
fastened  perfectly  parallel  with  the  centers  of  the  lathe. 
A  straight,  round  piece  of  iron,  of  equal  thickness,  and 
having  a  few  inches  in  the  center  of  a  square  shape,  mor- 
tised for  the  reception  of  cutters,  is  laid  on  these  knees, 
and  answers  the  purpose  of  a  handle  to  hold  the  cutting 
tools.  Two  handles  will  thus  hold  eight  tools,  one  set  for 
brass  and  one  for  steel.  On  every  side  of  the  square  part 
of  this  iron  bar,  or  what  we  will  now  call  the  turning  tool 
handle,  a  number  of  cutting  tools  are  fastened  by  set  screws, 
and  the  method  of  using  them  is  as  follows :  The  operator 
holds  the  tool  handle  with  both  hands  on  to  the  knees  that 
are  fastened  to  the  head  and  tail  stocks  of  the  lathe,  with 
the  turning  tool  that  is  desired  to  be  used  pointing  towards 
the  center,  and  it  is  allowed  to  come  in  contact  with  the 
work  running  in  the  lathe  in  the  usual  manner  practiced  in 
turning.  Fig.  76  is  from  a  photo  furnished  by  Mr.  H.  E. 
Smith  of  the  Smith  Novelty  Co.,  Hopewell,  N.  J.,  and 
shows  the  tools  in  the  rack,  w^hich  is  wound  with  leather 
so  that  the  tools  may  be  rapidly  thrown  in  place  without 
injury. 

If  a  plain,  straight  piece  of  work  is  to  be  turned,  the 
tool  is  adjusted  in  the  handle  so  that  the  work  will  be  of 
the  proper  diameter  when  the  round  parts  of  the  handle 
come  in  contact  with  the  perpendicular  part  of  the  knees 
or  rest;  and  while  the  handle  is  thus  held  and  moved  gently 


THE    MODERN    CI.OCK. 


247 


^]]I3         Stock  advanced. 


V 


p 


First  collet  driven. 


Second  collet  driven. 


Third  collet  driven. 


n 


Ri 


Shoulder  turned. 


First  sides  faced. 


Second  sides  faced. 


fO 


Pivots  turned. 


^]=n=I 


Pivots  burnished. 


Cut  oft. 


Fig.  78. 


Showing  Successive  Steps  in  Turning  on  Automatic  Pinion 
Making  Machine. 


248  THE    MODERN    CLOCK. 

along  in  the  corners  of  the  knees,  with  the  tool  sliding  on 
the  T-rest,  the  work  is  easily  turned  perfectly  parallel, 
smooth  and  true.  Sometimes  a  roughing  cut  is  taken  by 
holding  the  bar  loosely  and  then  a  finishing  cut  is  made 
with  the  same  tool  by  holding  it  firmly  in  place.  In  turning 
a  pinion  arbor,  for  instance,  the  wire  having  been  previously 
straightened  and  cut  to  length  and  centered,  and  the  brass 
collets  to  make  the  pinion  and  to  fasten  the  wheel  having 
l)een  driven  on,  one  end  is  held  in  the  lathe  by  a  spring 
chuck  fastened  to  the  spindle  of  the  lathe,  while  the  other 
end  works  in  a  center  in  the  other  head.  One  turning  tool 
is  shaped  and  adjusted  in  the  handle  for  the  purpose  of 
turning  the  brass  collets  for  the  pinion  to  the  proper  diam- 
eter, another  turns  the  sides  of  the  brass  work,  while  others 
are  adapted  for  the  arbors,  pivots,  and  so  on,  pins  being 
placed  in  holes  in  the  T-rest  to  act  as  stops  for  the  tools. 
After  the  brass  work  has  been  turned,  the  positions  of  the 
shoulders  of  the  pivots  are  marked  with  a  steel  gauge,  and 
by  simply  turning  round  the  handle  of  the  turning  tool  till 
the  proper  shaped  point  presents  itself,  each  operation  is 
accomplished  rapidly,  and  the  cutting  is  so  smooth  that 
even  for  the  pivots  all  that  is  necessary  to  finish  them  is 
simply  to  bring  them  in  contact  with  a  small  burnisher. 
The  article  is  not  taken  from  the  lathe  during  the  whole 
process  of  turning,  and  when  completed  the  centers  are 
broken  off,  having  been  previously  marked  pretty  deep  at 
the  proper  place  wi'th  a  cutting  point.  Five  hundred  to 
1,200  arbors  per  day,  per  man,  is  the  usual  output.  All 
the  pinions,  arbors,  and  barrels — in  fact  every  part  of  an 
American  clock  movement  that  requires  turning — were  for- 
merly done  in  this  manner,  at  long  rows  of  lathes  in  rooms, 
and  by  workmen  set  apart  for  the  purpose.  But  perhaps  it 
may  be  well  to  mention  that  in  the  machine  shops  of  these 
factories,  where  they  make  the  tools,  the  ordinary  methods 
of  turning  with  the  common  hand  tool,  and  by  the  aid  of 
ordinary  and  special  slide  rests,  are  practiced  the  same  as  it 


THE    MODERN    CLOCK. 


'49 


No.  79.    Automatic  Pinion  Drill  of  the  Davenport  Machine  Company. 


250  THE    MODERN    CLOCK. 

is  among  other  machinists.  In  the  large  factories  automatic 
turret  machines  are  now  coming  into  use  and  these  are 
shown  in  Figs.,  77,  78  and  79. 

The  lantern  pinions  of  an  American  clock  have  long  been 
a  mystery  to  those  unacquainted  with  the  method  of  their 
manufacture,  and  the  usual  accuracy  in  the  position  of  the 
small  wires  or  "rounds/'  combined  with  great  cheapness, 
has  often  been  a  subject  of  remark.  The  holes  for  the 
wires  in  these  pinions  are  drilled  in  a  machine  constructed 
as  follows:  An  iron  bed  with  two  heads  on  it,  Fig.  80,  one 
of  which  is  so  constructed  that  by  pulling  a  lever  the  spin- 
dle has  a  motion  lengthwise  as  well  as  the  usual  circular 
motion,  and  on  the  point  of  this  spindle,  which  is  driven  at 
22,000  revolutions,  the  drill  is  fastened  that  is  to  bore  tne 
holes  in  the  pinions ;  the  other  head  has  an  arbor  passing 
through  it  with  an  index  plate  attached,  having  holes  in  the 
plate,  and  an  index  finger  attached  to  a  strong  spring  going 
into  the  holes,  the  same  as  in  a  wheel-cutting  engine;  on 
this  head,  and  on  the  end  of  it  that  faces  the  drill,  there  is 
a  frame  fastened  in  which  the  pinion  that  is  to  be  bored 
is  placed  between  centers,  and  is  carried  round  with  the 
arbor  of  the  index  plate,,  in  the  same  manner  as  a  piece  of 
work  is  carried  round  in  an  ordinary  lathe  by  means  of  a 
dog,  or  carrier;  only  in  the  pinion  drilling  machine  the 
carrier  is  so  constructed  that  there  is  no  shake  in  any  way 
between  the  pinion  and  the  index  arbor.  This  head  is  car- 
ried on  a  slide  having  a  motion  at  right  angles  to  the  spindle 
of  the  other  head,  by  w^iich  means  the  pitch  diameter  of 
the  proposed  pinion  is  adjusted.  The  head  is  moved  in  the 
slide  by  an  accurately  cut  screw,  to  which  a  micrometer  is 
attached  that  enables  the  workman  to  make  an  alteration 
in  the  diameter  of  a  pinion  as  small  as  the  one-thousandth 
part  of  an  inch.  The  drill  that  bores  the  holes  is  the  ordi- 
nary flat-pointed  drill,  and  has  a  shoulder  on  its  stem  that 
stops  the  progress  of  the  drill  when  it  has  gone  through 
the  first  part  of  the  pinion  head  and  nearly  through  the 


THE    MODERN    CLOCK. 


251 


other.  All  operators  make  their  own  drills  and  the  limits 
of  error  are  for  pitch  diameter  .0005  inch;  error  of  size  of 
drills  .0001.  The  reader  can  see  that  these  men  must  know 
something  of  drill  making. 

The  action  of  the  machine  is  simple.     The  pinion,  after 
it  has  been  turned,  pivoted  and  dogged,  is  placed  in  its 


Fig.  80.    Pinion  Drilling  Machine. 


position  in  the  machine,  and  by  pulling  a  lever,  the  drill, 
which  is  running  at  a  speed  of  about  22,000  revolutions  a 
minute,  comes  in  contact  with  the  brass  heads  of  the  pinion 
and  bores  the  one  through  and  the  other  nearly  through. 
The  lever  is  then  let  go,  and  a  spring  pulls  the  drill  back  ; 
the  index  is  turned  round  a  hole,  and  another  hole  bored  in 
the  pinion,  and  so  on  till  all  the  holes  are  bored.  An  ordi- 
nary expert  workman,  with  a  good  machine,  will  bore 
about  fourteen  hundred  of  medium-sized  pinions  in  a  day. 


25^ 


THE    MODERN    CLOCK. 


The  wires  or  ''rounds"  are  cut  from  drill  rod  and  are  put 
into  the  holes  by  hand  by  girls  who  become  very  expert  at 
it.  This  is  called  "filling."  We  have  already  stated  that 
the  holes  are  only  bored  partly  through  one  of  the  pieces 
of  the  brass,  and  after  the  wire  has  been  put  in,  the  holes 
are  riveted  over,  and  in  this  manner  the  wires  are  fastened 
so  that  they  cannot  come  out.  Some  factories  close  the 
holes  by  a  thin  brass  washer  forced  on  the  arbor,  instead  of 
riveting. 

Figs,  "j^j,  78  and  79  show  the  automatic  pinion  turning 
machine  and  its  processes  in  successive  operations.  These 
machines  are  used  by  most  of  the  large  clock  manufacturers 
of  the  United  States  and  some  of  the  European  concerns 
also.  They  are  entirely  automatic,  will  make  1,500  pinions 
per  day,  as  an  average,  and  one  man  can  run  four  ma- 
chines. 

Fig.  79  shows  an  automatic  pinion  drilling  machine, 
which  takes  up  the  work  where  it  is  left  by  the'  machine 
shown  in  Fig.  ']'].  This  machine  will  drill  4,000  to  5,000 
pinions  per  day  according  to  the  size  hole  and  the  number 
of  holes.  The  operator  places  the  pinions  in  the  special 
chain  shown  in  the  front  of  the  machine,  from  which  the 
transport  arms  ca^*-y  them  to  the  spindle,  where  they  are 
drilled  and  when  completed  drop  out.  One  operator  can 
feed  three  of  these  machines. 

Making  Solid  Pinions. — The  solid  steel  pinions  are  not 
hardened,  but  are  made  of  Bessemer  steel,  which  could  only 
be  case  hardened — a  thing  hardly  ever  done.  The  process 
of  making  these  pinions  is  as  follows :  Rods  of  Bessemer 
steel  are  cut  into  suitable  lengths.  The  pieces  obtained  are 
pointed  or  centered  on  both  ends.  The  stock  not  needed  for 
the  pinion  head  is  cut  away,  leaving  the  arbors  slightly 
tapering,  for  the  purpose  of  fastening  them  by  this  means 
in  a  hole  on  the  cutting  machine.  On  the  end  of  the  arbor 
of  the  index  plate  are  two  deep  cuts  across  its  center,  and 


THE    MODERN    CLOCK.  253 

at  right  angles  to  each  other.  These  cuts  are  of  the  same 
shape  that  would  be  made  by  a  knife-edged  file.  The  effect 
of  these  cuts  is  to  produce  a  taper  hole  in  the  end  of  the 
arbor,  with  four  sharp  corners.  Into  this  hole  the  end  of 
the  arbor  of  the  pinion  or  ratchet  that  is  to  be  cut  is  placed, 
and  a  spring  center  presses  on  the  other  end,  and  the  sharp 
corners  in  the  hole  hold  the  work  firm  enough  to  prevent  it 
from  turning  round  when  the  teeth  are  being  cut.  The 
marks  that  are  to  be  seen  on  the  shoulder  of  the  back  pivot 
of  the  arbor  that  carries  the  minute  hand  of  a  Yankee  clock 
is  an  illustration  of  this  method  of  holding  the  pinion  when 
the  leaves  are  being  cut,  and  no  injurious  effects  arise  from 
it.  The  convenience  the  plan  affords  for  fastening  work  in 
the  engine  enables  twenty-five  hundred  of  these  pinions  to 
be  cut  in  a  day,  one  at  a  time.  The  pinion  head  is  cut  sub- 
ject to  the  proper  dividing  plate  by  a  splitting  circular  saw, 
and  by  a  milling  tool  (running  in  oil)  for  forming  the  shape 
of  the  leaves,  both  of  which  tools  are  generally  carried  on 
the  same  arbor,  both  being  shifted  into  their  proper  places 
by  an  adjusting  attachment.  Pinion  leaves  of  the  better 
class  are  generally  shaped  by  two  succeeding  milling  cut- 
ters, the  second  one  of  which  does  the  finishing,  obviating 
any  other  smoothing.  For  very  cheap  work  the  arbors  re- 
ceive no  further  finish.  The  shaping  of  the  pivots,  done  by 
an  automatic  lathe,  finishes  the  job. 

Figure  8i  shows  an  automatic  pinion  cutting  machine 
which  has  extensive  use  in  clock  factories  for  cutting  pinions 
up  to  one-half  inch  diameter  and  also  the  smaller  wheels. 
For  wheels  the  work  is  handled  in  stacks  suited  to  the  tra- 
verse of  the  machine,  the  work  being  treated  as  if  the  stacks 
were  long  brass  pinions. 

Wheels  are  cut  in  two  ways,  on  automatic  wheel  cutters 
as  just  described  and  on  engines  containing  parallel  spindles 
for  the  cutters,  carried  in  a  yoke  which  rises  and  falls,  so 
that  it  clears  the  work  while  the  carriage  is  returning  to 
the  starting  point  on  each  trip  and  engages  it  on  the  out- 


254 


THE    MODERN    CLOCK. 


ward  trip.  The  cutters  are  about  three  inches  in  diameter 
and  rapidly  driven;  the  first  is  a  saw,  the  second  a  roughing 
cutter,  and  the  third  a  finishing  cutter.     The  carriage  is 


Fig.  81.    Automatic  Wheel  and  Pinion  Cutters. 


driven  by  a  rack  and  pinion  operated  by  a  crank  in  the 
hands  of  the  workman  and  streams  of  soda  water  are  used 
on  the  cutters  and  work  to  carry  away  the  heat,  as  brass 
expands  rapidly  under  heat,  and  if  the  stack  were  cut  dry 


THE    MODERN    CLOCK. 


255 


the  cut  would  get  deeper  as  the  cutting  proceeded,  owing 
to  the  expansion  of  the  brass,  and  hence  the  finished  wheel 
would  not  be  round  when  cold,  if  many  teeth  were  being 
cut.  The  stacks  of  wheels  are  about  four  inches  in 
length  and  the   slide  thus  travels   about  twenty   inches   in 


Fig.  82.    Wheel  Cutting  Engine. 


order  to  clear  the  three  arbors  and  engage  with  the  shifter 
for  the  index.  The  last  wheel  of  the  stack  has  a  very  large 
burr  formed  by  the  cutters  as  they  leave  the  brass  and  this 
wheel  is  removed  from  the  stack  when  the  arbor  is  taken 
out  and  placed  aside  to  have  the  burrs  removed  by  rubbing 
on  emery  paper. 


256  THE    MODERN    CLOCK. 

■This  is  one  of  the  few  instances  in  which  automatic  ma- 
chinery has  been  unable  to  displace  hand  labor,  as  the  work 
is  done  so  quickly  that  the  time  of  the  attendant  would  be 
nearly  all  taken  up  in  placing  and  removing  the  stacks, 
and  so  the  feeding  is  done  by  him  as  well.  About  35,000 
wheels  per  day  can  be  thus  cut  by  one  man,  with  girls  to 
stack  the  blanks  on  the  arbors,  and  an  automatic  feed  would 
not  release  the  man  from  attendance  on  the  machine,  so 
that  the  majority  of  clock  wheels  are  cut  to-day  as  they 
were  forty  years  ago.  Still,  some  of  the  factories  are  add- 
ing an  automatic  feed  to  the  carriage  in  the  belief  that  the 
increased  evenness  of  feed  will  give  a  more  accurately  cut 
wheel,  a  proposition  which  the  men  most  vigorously  deny. 
Such  a  machine,  they  say,  to  be  truly  automatic,  miust  take 
its  stacks  of  wheels  from  a  magazine  and  discharge  the 
work  when  done,  so  that  one  attendant  could  look  after  a 
number  of  machines.  This  would  result  in  economy,  as  well 
as  accuracy,  but  has  not  been  done  owing  to  the  great  vari- 
ations in  sizes  of  wheels  and  numbers  of  teeth  required  in 
clock  work. 

Figure  82  shows  one  of  these  machines,  a  photograph  of 
which  was  taken  especially  for  us  by  the  courtesy  of  the 
Seth  Thomas  Clock  Company  at  their  factory  in  Thomas- 
ton,  Conn. 

About  every  ten  years  some  factory  decides  to  try  stamp- 
ing out  the  teeth  of  wheels  at  the  same  time  they  are  being 
blanked ;  this  can,  of  course,  be  done  by  simply  using  a 
more  expensive  punch  and  die,  and  at  first  it  looks  very  at- 
tractive ;  but  it  is  soon  found  that  the  cost  of  keeping  up 
such  expensive  dies  makes  the  wheels  cost  more  than  if 
regularly  cut  and  for  reasons  of  economy  the  return  is 
made  to  the  older  and  better  looking  cut  wheels. 

After  an  acid  dip  to  remove  the  scale  on  the  sheet  brass, 
followed  by  a  dip  in  lacquer,  to  prevent  further  tarnish, 
the  wheels  are  riveted  on  the  pinions  in  a  specially  con- 
structed jig  which  keeps  them  central  during  the  rivetting 


THE    MODERN    CLOCK.  257 

and  when  finished  the  truth  of  every  wheel  and  its  pinions 
and  pivots  are  all  tested  before  they  are  put  into  the  clocks. 
The  total  waste  on  all  processes  in  making  wheels  and  pin- 
ions is  from  two  to  five  per  cent,  so  that  it  will  readily  be 
seen  that  accuracy  is  demanded  by  the  inspectors.  Euro- 
pean writers  have  often  found  fault  with  nearly  everything 
else  about  the  Yankee  clock,  but  they  all  unite  in  agreeing 
that  the  cutting  and  centering  of  wheels,  pinions  and  pivots 
(and  the  depthing)  are  perfect,  while  the  clocks  of  Ger- 
many, France,  Switzerland  and  England  (particularly 
France)  leave  much  to  be  desired  in  this  respect;  and  much 
of  the  reputation  of  the  Yankee  clock  in  Europe  corties  from 
the  fact  that  it  will  run  under  conditions  which  would  stop 
those  of  European  make. 

We  give  herewith  a  table  of  clock  trains  as  usually  manu- 
factured, from  which  lost  wheels  and  pinions  may  be  easily 
identified  by  counting  the  teeth  of  wheels  and  pinions  which 
remain  in  the  movement  and  referring  to  th-e  table.  It  will 
also  assist  in  getting  the  lengths  of  missing  pendulums  by 
counting  the  trains  and  referring  to  the  corresponding 
length  of  pendulums.  Thus,  with  84  teeth  in  the  center 
wheel,  70  in  the  third,  30  in  the  escape  and  7-leaf  pinions, 
the  clock  is  120  beat  and  requires  a  pendulum  9.78  inches 
from  the  bottom  of  suspension  to  the  center  of  the  bob. 

To  Calculate  Clock  Trains. — Britten  gives  the  fol- 
lowing rule:  Divide  the  number  of  pendulum  vibrations 
per  hour  by  twice  the  number  of  escape  wheel  teeth;  the 
quotient  will  be  the  number  of  turns  of  escape  wheel  per 
hour.  Multiply  this  quotient  by  the  number  of  escape 
pinion  teeth,  and  divide  the  product  by  the  number  of  third 
wheel.  This  quotient  will  be  the  number  of  times  the  teeth 
of  third  wheel  pinion  must  be  contained  in  center  wheel. 

Take  a  pendulum  vibrating  5,400  times  an  hour,  escape 
wheel  of  30,  pinions  of  8,  and  third  wheel  of  ']2.  Theri 
5,40CK-6o=90.     And  90X8-^-72=10.     That  is,  the  center 


258 


THE    MODERN    CLOCK. 


Clock  Trains  and  Lengths  of  Pendulums* 


"  1 

o 

to    ,     r! 

If 

5?'2  c 

V) 

,o 

c4  <1> 

m 

III 

§ 

1 

"c 

120    90    75 

10  10  9 

Double 

*30 

156.56 

96    76 

8 

30 

114 

10.82 

31eg- 

115  100 

10 

30 

115 

10-65 

ffo' 

84    78 

7 

26 

115.9 

10.49 

120    90    90 

10    9  9 

*40 

88.07 

96    80 

8 

30 

120 

9.78 

128  120 

16 

30 

60 

39.14 

84    70 

7 

30 

120 

9.78 

112  105 

14 

30 

60 

39.14 

84    78 

7 

27 

120.3 

9.73 

96    90 

12 

30 

60 

39.14 

90    84 

8 

31 

122 

9.46 

80    75 

10 

30 

60 

39.14 

84    78 

7 

28 

124.8 

9.02 

64    60 

8 

30 

60 

39.14 

100    80 

8 

30 

125 

9.01 

68    64 

8 

30 

68 

30.49 

90    84 

8 

32 

126 

8.87 

70    64 

8 

30 

70 

28.75 

100    96 

10 

40 

128 

8.59 

72    64 

8 

30 

72 

27.17 

84    78 

7 

29 

129.3 

8.42 

75    60 

8 

32 

75 

25.05 

100    78 

8 

32 

130 

8.34 

72    65 

8 

32 

78 

23.15 

84    77 

7 

30 

132 

8.08 

75    64 

8 

32 

80 

22.01 

84    78 

7 

30 

133.7 

7.9 

84    64 

8 

30 

84 

19.97 

90    90 

8 

32 

135 

7.73 

86    64 

8 

30 

86 

19.06 

84    78 

7 

31 

138.2 

7.38 

88    64 

8 

30 

88 

18.19 

84    80 

8 

40 

140 

7.18 

84    78 

7 

20 

89.1 

17.72 

120    71 

8 

32 

142 

6.99 

80    72 

8 

30 

90 

17.39 

84    78 

7 

32 

142.6 

6.93 

84    78 

7 

21 

93.6 

16.08 

100    87 

8 

32 

145 

6.69 

94    64 

8 

30 

94 

15.94 

84    78 

7 

33 

147.1 

6.5 

84    78 

8 

■    28 

95.5 

15.45 

100    96 

8 

30 

150 

6.26 

108  100 

12&10 

32 

96 

15.28 

84    78 

7 

34 

151.6 

6.1 

84    84 

9&  8 

30 

98 

14.66 

96    95 

8 

32 

152 

6.09 

84    78 

7 

22 

98 

14.66 

84    77 

7 

35 

154 

5.94 

84    78 

8 

29 

98.9 

14.41 

104    96 

8 

30 

156 

5.78 

80    80 

8 

30 

100 

14.09 

84    78 

7 

35 

156 

5.78 

85    72 

8 

32 

102 

13.54 

120    96 

9&8 

30 

160 

5.5 

84    78 

8 

30 

102.4 

13.44 

84    78 

7 

36 

160.5 

5.47 

84    78 

7 

23 

102.5 

13.4 

84    78 

7 

37 

164.9 

5.15 

105  100 

10 

30 

105 

12.78 

132  100 

9&8 

27 

165 

5.17 

84    78 

8 

31 

105.8 

12.59 

84    78 

7 

38 

169.4 

4.88 

84    78 

7 

24 

107 

12.3 

128  102 

8 

25 

170 

4.87 

96    72 

8 

30 

108 

12.08 

84    78 

7 

39 

173.8 

4.65 

84    78 

8 

32 

109.2 

11.82 

36    36    35 

6 

25 

175 

4.6 

88    80 

8 

30 

110 

11.64 

84    77 

7 

40 

176 

4.55 

84    77 

7 

25 

110 

11.64 

84    78 

7 

40 

178.3 

4.43 

84    78 

7 

25 

111.4 

11.35 

45    36    36 

6 

20 

180 

4.35 

84    80 

8 

32 

112 

11.22 

47    36    36 

6 

20 

188 

3.99 

84    78 

8 

33 

112.6 

11.11 

*These  are  good  examples  of  turret  clock  trains;  the  great  wheel  (120  teeth) 
malces  in  both  instances  a  rotation  in  three  hours,  From  this  wheel  the  hands 
are  to  be  driven.  This  may  be  done  by  means  of  a  pinion  of  40  gearing  with  the 
great  wheel,  or  a  pair  of  bevel  wheels  bearing  the  same  proportion  to  each 
other  (three  to  one)  may  be  used,  the  larger  one  being  fixed  to  the  great  wheel 
arbor.  The  arrangement  would  in  each  case  depend  upon  the  number  and  posi- 
tion of  the  dials.  The  double  three-legged  gravity  escape  wheel  moves  through 
60°  at  each  beat,  and  therefore  to  apply  the  rule  given  for  calculating  clock 
•trains  it  must  be  treated  as  an  escape  wheel  of  three  teeth. 


THE    MODERN    CLOCK. 


259 


wheel  must  have  ten  times  as  many  teeth  as  the  third  wheel 
pinion,  or  ten  times  8=80. 

The  center  pinion  and  great  wheel  need  not  be  consid- 
ered in  connection  with  the  rest  of  the  train,  but  only  in 
relation  to  the  fall  of  the  weight,  or  turns  of  mainspring, 
as  the  case  may  be.  Divide  the  fall  of  the  weight  (or  twice 
the  fall,  if  double  cord  and  pulley  are  used)  by  the  circum- 
ference of  the  barrel  (taken  at  the  center  of  the  cord)  ; 
the  quotient  will  be  the  number  of  turns  the  barrel  must 
make.  Take  this  number  as  a  divisor,  and  the  number  of 
turns  made  by  the  center  wheel  during  the  period  from 
winding  to  winding  as  the  dividend;  the  quotient  will  be 
the  number  of  times  the  center  pinion  must  be  contained  in 
the  great  wheel.  Or  if  the  numbers  of  the  great  wheel  and 
center  pinion  and  the  fall  of  the  weight  are  fixed,  to  find 
the  circumference  of  the  barrel,  divide  the  number  of  turns 
of  the  center  wheel  by  the  proportion  between  the  center 
pinion  and  the  great  wheel ;  take  the  quotient  obtained  as  a 
divisor,  and  the  fall  of  the  weight  as  a  dividend  (or  twice 
the  fall  if  the  pulley  is  used),  and  the  quotient  will  be  the 
circumference  of  the  barrel.  To  take  an  ordinary  regulator 
or  8-day  clock  as  an  example — 192  (number  of  turns  of 
center  pinion  in  8  days)-i-i2  (proportion  between  center 
pinion  and  barrel  wheel) :=  16  (number  of  turns  of  barrel). 
Then  if  the  fall  of  the  cord^  40  inches,  40X2-^16=5, 
which  would  be  circumference  of  barrel  at  the  center  of  the 
cord. 

If  the  numbers  of  the  wheels  are  given,  the  vibrations  per 
hour  of  the  pendulum  may  be  obtained  by  dividing  the  prod- 
uct of  the  wheel  teeth  multiplied  together  by  the  product  of 
the  pinions  multiplied  together,  and  dividing  the  quotient  by 
twice  the  number  of  escape  wheel  teeth. 

The  numbers  generally  used  by  clock  makers  for  clocks 
with  less  than  half-second  pendulum  are  center  wheel  84, 
gearing  with  a  pinion  of  7 ;  third  wheel  78,  gearing  with  a 
pinion  of  7. 


26o'  THE    MODERN    CLOCK. 

■  The'  product  obtained  by  multiplying  too^ether  the  center 
pnd  third  wheels=84X78=6,552.  The  two  pinions  multi- 
plied tcgether=7X7=49-  Then  6,552^-49=133.7.  So 
that  for  every  turn  of  the  center  wheel  the  escape  pinion 
turns  133.7  times.  Or  133.7-^60=2.229,  which  is  the  num- 
ber of  turns  in  a  minute  of  the  escape  pinion. 

The  length  of  the  pendulum,  and  therefore  the  number 
of  escape  wheel  teeth,  in  clocks  of  this  class  is  generally  de- 
cided with  reference  to  the  room  to  be  had  in  the  clock 
case,  with  this  restriction,  the  escape  wheel  should  not  have 
less  than  20  nor  more  than  40  teeth,  or  the  performance  will 
not  be  satisfactory.  The  length  of  the  pendulum  for  all 
escape  wheels  within  this  limit  is  given  in  the  preceding 
table.  The  length  there  stated  is  of  course  the  theoretical 
length,  and  the  ready  rule  adopted  by  clockmakers  is 
to  measure  from  the  center  arbor  to  the  bottom  of  the 
inside  of  the  case,  in  order  to  ascertain  the  greatest  length 
of  pendulum  which  can  be  used.  For  instance,  if 
from  the  center  arbor  to  the  bottom  of  the  case  is  10  inches, 
they  would  decide  to  use  a  lo-inch  pendulum,  and  cut  the 
escape  wheel  accordingly  with  the  number  of  teeth  required 
as  shown  in  the  table.  But  they  would  make  the  pendulum 
rod  of  such  a  length  as  just  to  clear  the  bottom  of  the  case 
when  the  pendulum  was  fixed  in  the  clock. 

In  the  clocks  just  referred  to  the  barrel  or  first  wheel 
has  96  teeth,  and  gears  with  a  pinion  of  eight. 

Month  clocks  have  an  intermediate  wheel  and  pinion  be- 
tween the  great  and  center  wheels.  This  extra  wheel  and 
pinion  must  have  a  proportion  to  each  other  of  4  to  i  to 
enable  the  8-day  clock  to  go  2i'^  days  from  winding  to  wind- 
ing. The  weight  will  have  to  be  four  times  as  h^avy,  plus 
the  extra  friction,  or  if  the  same  weight  is  used  there  must 
be  a  proportionately  longer  fall. 

Six-months  clock  have  two  extra  wheels  and  pinions  be- 
tween the  great  and  center  wheels,  one  pair  having  a  pro- 
portion of  4^  to  I  and  the  other  of  6  to  i.    But  there  is  an 


THE    MODEliX    CLOCK.J      rlJl^j^      Af  4  o         ^ 

enormous  amount  of  extra  friction  generated  in  these  clocks, 
and  they  are  not  to  be  recommended. 

The  pivot  holes  and  all  the  other  holes  in  the  frames,  are 
punched  at  one  operation  after  the  frames  have  been 
blanked  and  flattened.  They  are  placed  in  the  press,  and 
a  large  die  having  punches  in  it  of  the  proper  size  and 
in  the  right  position  for  the  holes,  comes  down  on  the  frame 
and  makes  the  holes  with  great  rapidity  and  accuracy. 
These  holes  are  finished  afterwards  by  a  broach.  In  some 
kinds  of  clocks,  where  some  of  the  pivot  holes  are  very 
small,  the  small  holes  are  simply  marked  with  a  sharp  point 
in  the  die,  and  afterwards  drilled  by  small  vertical  drills. 
These  machines  are  very  convenient  for  boring  a  number 
of  holes  rapidly.  The  drill  is  rotated  with  great  speed,  and 
a  jig  or  plate  on  which  the  work  rests  is  moved  upwards 
towards  the  drill  by  a  movement  of  the  operator's  foot.  All 
the  boring,  countersinking,  etc.,  in  American  clocks,  is  done 
through  the  agency  of  these  drills.  Bending  the  small 
wires  for  the  locking  work,  the  pendulum  ball,  etc.,  is  rap- 
idly effected  by  forming.  As  no  objectionable  marks  have 
been  made  on  the  surface  of  either  the  thick  or  smaller 
wires  during  any  process  of  construction,  all  that  is  neces- 
sary to  finish  the  iron  work  is  simply  to  clean  it  well,  which 
is  done  in  a  very  effective  manner  by  placing  a  quantity  of 
work  in  a  revolving  tumbling  box,  which  is  simply  a  barrel 
containing  a  quantity  of  saw-dust. 

Milling  the  winding  squares  on  barrel  arbors  is  an  in- 
genious operation.  The  machine  for  milling  squares  and 
similar  work  is  made  on  the  principle  of  a  wheel-cutting  en- 
gine. The  work  is  held  in  a  frame,  attached  to  which  is  a 
small  index  plate,  like  that  of  a  cutting  engine.  In  the  ma- 
chine two  large  mills  or  cutters,  with  teeth  in  them  like  a 
file,  are  running,  and  the  part  to  be  squared  is  moved  in 
between  the  revolving  cutters,  which  operation  immediately 
forms  two  sides  of  the  square.  The  work  is  then  drawn 
back,  and  the  index  turned  round,  and  in  a  like  manner  the 


262  THE    MODERN    CLOCK. 

other  two  sides  of  the  square  are  formed.  The  cutting- 
sides  of  the  mills  are  a  little  bevelled,  so  that  they  will  pro- 
duce a  slight  taper  on  the  squares. 

Winding  keys  have  shown  great  improvements.  Some 
manufacturers  originally  used  cast  iron  ones,  but  the  squares 
were  never  good  in  them,  and  brass  ones  were  adopted.  At 
first  the  squares  were  made  by  first  drilling  a  hole  and  driv- 
ing a  square  punch  in  with  a  hammer;  and  to  make  the 
squares  in  eighteen  hundred  keys  by  this  method  was  con- 
sidered a  good  day's  work.  Restless  Yankee  ingenuity, 
however,  has  contrived  a  device  by  which  twenty  or  twen- 
ty-five thousand  squares  can  be  made  in  a  day,  while  at  the 
same  time  they  are  better  and  straighter  squares  than  those 
by  the  old  method;  but  we  are  not  at  hberty  to  describe 
the  process  at  present,  but  only  to  state  that  it  is  done 
by  what  machinists  call  drilHng  a  square  hole. 

Pendulum  rods  are  made  from  soft  iron  wire,  and  the 
springs  on  the  ends  rolled  out  by  rollers.  Two  operations 
are  necessary.  The  first  roughs  the  spring  out  on  rollers 
of  eccentric  shape,  and  the  spring  is  afterwards  finished  on 
plain  smooth  rollers.  The  pendulum  balls  in  the  best  clocks 
are  made  of  lead,  on  account  of  its  weight,  and  cast  in  an 
iron  mold  in  the  same  manner  as  lead  bullets,  at  the  rate 
of  about  eighteen  hundred  a  day.  A  movable  mandrel  is 
placed  in  the  mold  to  produce  the  hole  that  is  in  the  center 
of  the  ball.  The  balls  are  afterwards  covered  with  a  shell 
of  brass,  polished  with  a  blood-stone  burnisher.  The  vari- 
ous cocks  used  in  these  clocks  are  all  struck  up  from  sheet 
brass,  and  the  pins  in  the  wheels  in  the  striking  part  are  all 
swedged  into  their  shape  from  plain  wire.  The  hands  are 
die  struck  out  of  sheet  steel,  and  afterwards  polished  on 
emery  belts,  and  blued  in  a  furnace. 

All  the  little  pieces  of  these  clocks  are  riveted  together  by 
hand,  and  the  different  parts  of  the  movement,  when  com- 
plete, are  put  together  by  workmen  continually  employed 
in  that  department.    Although  the  greatest  vigilance  is  used 


THE    MODERN    CLOCK.  26^ 

in  constructing  the  different  parts  to  see  that  they  are  per- 
fect, when  they  come  to  be  put  together  they  are  subjected 
to  another  examination,  and  after  the  movements  are  put 
in  the,  case  the  clocks  are  put  to  the  test  by  actual  trial  be- 
fore they  are  packed  ready  for  the  market.  As  a  general 
rule,  all  the  different  operations  are  done  by  workmen  em- 
ployed only  at  one  particular  branch;  and  in  the  largest 
factories  from  thirty  to  fifty  thousand  clocks  of  all  classes 
may  be  seen  in  the  various  stages  of  construction. 

Such  is  a  description  of  the  main  points  in  which  the  man- 
ufacture of  American  clock  movements  differs  from  those 
manufactured  by  other  systems.  All  admit  that  these  clocks 
perform  the  duties  for  which  they  are  designed  in  an  ad- 
mirable manner,  while  they  require  but  little  care  to  m.an- 
age,  and  when  out  of  order  but  little  skill  is  necessar^^  to 
repair  them.  Of  late  years  there  has  been  a  growing  de- 
mand for  ornamental  mantel-piece  clocks  in  metallic  cases 
of  superior  quality,  and  large  numbers  of  these  cases  of 
both  bronze  and  gold  finish  are  being  manufactured,  which, 
for  beauty  of  design  and  fine  execution,  in  many  instances 
rival  those  of  French  production.  The  shapes  of  the  ordi- 
nary American  movements  were,  however,  unsuitable  for 
some  patterns  of  the  highest  class  of  cases,  and  the  full  plate, 
round  movements  of  the  same  size  as  the  French,  but  with 
improvements  in  them  that  in  some  respects  render  them 
more  simple  than  the  French,  are  now  manufactured.  Ex- 
actly the  same  system  is  employed  in  the  manufacture  of 
the  different  parts  of  these  clocks  that  is  practiced  in  mak- 
ing the   ordinary  American   movements. 


CHAPTER  XV. 

SPRINGS,   WEIGHTS  AND  POWER. 

We  see  by  the  preceding  calculations  that  there  is  one 
definite  point  in  the  time  train  of  a  clock ;  the  center  arbor, 
which  carries  the  minute  hand,  must  revolve  once  in  one 
hour;  from  this  point  we  may  vary  the  train  both  ways, 
toward  the  escape  wheel  to  suit  the  length  of  pendulum 
which  we  desire  to  use,  and  toward  the  barrel  to  suit  the 
length  of  time  we  want  the  clock  to  run.  The  center  arbor 
is  therefore  generally  used  as  the  point  at  which  to  begin 
calculations,  and  it  is  also  for  this  reason  that  the  number 
of  teeth  in  the  center  wheel  is  the  starting  point  in  train 
calculations  toward  the  escape  wheel,  while  the  center  pinion 
is  the  starting  point  in  calculations  of  the  length  of  time  the 
weight  or  spring  is  to  drive  the  clock.  Most  writers  on 
horology  ignore  this  point,  because  it  seems  self-evident, 
but  its  omission  has  been  the  cause  of  much  mystification 
to  so  many  students  that  it  is  better  to  state  it  in  plain  terms, 
so  that  even  temporary  confusion  may  be  avoided. 

Sometimes  there  is  a  second  fixed  point  in  a  time  train ; 
this  occurs  only  when  there  is  a  seconds  hand  to  be  provided 
for;  when  this  is  the  case  the  seconds  hand  must  revolve 
once  every  minute.  If  it  is  a  seconds  pendulum  the  hand  is 
generally  carried  on  the  escape  wheel  and  the  relation  of 
revolutions  between  the  hour  and  seconds  wheels  must  then 
be  as  one  is  to  sixty.  This  might  be  accomplished  with  a 
single  wheel  having  sixty  times  as  many  teeth  as  the  pinion 
on  the  seconds  arbor ;  but  the  wheel  would  take  up  so  much 
room,  on  account  of  its  large  circumference,  that  the  move- 
ment would  become  unwieldly  because  there  would  be  no 
room,  left  for  the  other  wheels;  so  it  is  cheaper  to  make 

264 


THE    MODERN    CLOCK.  265 

more  wheels  and  pinions  and  thereby  get  a  smaller  clock. 
Now  the  best  practical  method  of  dividing  this  motion  is  by 
giving  the  wheels  and  pinions  a  relative  velocity  of  seven 
and  a  half  and  eight,  because  7.5  X  8  =  60. 

Thus  if  the  center  wheel  has  80  teeth,  gearing  into  a 
pinion  of  10,  the  pinion  will  be  driven  eight  times  for  each 
revolution  of  the  center  wheel,  while  the  third  wheel,  with 
75  teeth,  will  drive  its  pinion  of  10  leaves  7.5  times,  so  that 
this  arbor  will  go  7.5  times  eight,  or  60  times  as  fast  as  the 
center  wheel. 

If  the  clock  has  no  seconds  hand  this  second  fixed  point 
is  not  present  in  the  calculations  and  other  considerations 
may  then  govern.  These  are  generally  the  securing  of  an 
even  motion,  with  teeth  of  wheels  and  pinions  properly 
meshing  into  each  other,  without  incurring  undue  expense 
in  manufacture  by  making  too  many  teeth  in  the  pinions 
and  consequently  in  the  wheels.  For  these  reasons  pinions 
of  less  than  seven  or  more  than  ten  leaves  are  rarely  used 
in  the  common  clocks,  although  regulators  and  fine  clocks, 
where  the  depthing  is  important,  frequently  have  12,  14  or 
16  leaves  in  the  pinions,  as  is  also  the  case  with  tower  clocks, 
where  the  increased  size  of  the  movement  is  not  as  impor- 
tant as  a  smoothly  running  train.  Clocks  without  pendu- 
lums, carriage  clocks,  locomotive  levers  and  nickel  alarms, 
also  have  different  trains,  many  of  which  have  the  six  leaf 
pinion,  with  its  attendant  evils,  in  their  trains. 

Weights. — Weights  have  the  great  advantage  of  driving 
a  train  with  uniform  power,  which  a  spring  does  not  ac- 
complish :  They  are  therefore  always  used  where  exactness 
of  time  is  of  more  importance  than  compactness  or  porta- 
bility of  the  clock.  In  making  calculations  for  a  weight 
movement,  the  first  consideration  is  that  as  the  coils  of  the 
cord  must  be  side  by  side  upon  the  barrel  and  each  takes  up 
a  definite  amount  of  space,  a  thicker  movement  (with  longer 
arbors)   will  be  necessary,  as  the  barrel  must  give  a  suf- 


266  THE    MODERN    CI.OCK. 

ficient  number  of  turns  of  the  cord  to  run  the  clock  the 
desired  time  and  the  length  of  the  barrel,  with  the  wheel  and 
maintaining  power  all  mounted  upon  the  one  arbor,  will  de- 
termine the  thickness  of  the  movement.  If  the  clock  is  to 
have  striking  trains  their  barrels  will  generally  be  of  more 
turns  and  consequently  longer  than  the  time  barrel  and  in 
that  case  the  distance  between  the  plates  is  governed  by 
the  length  of  the  longest  barrel  and  its  mechanism. 

The  center  wheel,  upon  the  arbor  of  which  sits  the  canon 
pinion  with  the  minute  hand,  must,  since  the  hand  has  to 
accomplish  its  revolution  in  one  hour,  also  revolve  once  in 
an  hour.  When,  therefore,  the  pinion  of  the  center  arbor 
has  8  leaves  and  the  barrel  wheel  144,  then  the  8  pinion 
leaves,  which  makes  one  revolution  per  hour,  would  require 
the  advancing  of  8  teeth  of  the  barrel  wheel,  which  is  equal 
to  the  eighteenth  part  of  its  circumference.  But  when  the 
eighteenth  part  in  its  advancing  consumes  i  hour,  then  the 
entire  barrel  wheel  will  consume  18  hours  to  accomplish  one 
revolution.  If,  now,  10  coils  of  the  weight  cord  were  laid 
around  the  barrel,  the  clock  would  then  run  10  X  18  =  180 
hours,  or  7^.  days,  before  it  is  run  down. 

Referring  to  what  was  said  in  a  previous  chapter  on 
wheels  being  merely  compound  levers,  it  will  be  seen  that 
as  we  gain  motion  we  lose  power  in  the  same  ratio.  We 
shall  also  see  that  by  working  the  rule  backwards  we  may 
arrive  at  the  amount  of  force  exerted  on  the  pendulum  by 
the  pallets.  If  we  multiply  the  circumference  of  the  escape 
wheel  in  inches  by  the  number  of  its  revolutions  in  one  hour 
we  will  get  the  number  of  inches  of  motion  the  escape  wheel 
has  in  one  hour.  Now  if  we  multiply  the  weight  by  the 
distance  the  barrel  wheel  travels  in  one  hour  and  divide  by 
the  first  number  we  shall  have  the  force  exerted  on  the  es- 
cape wheel.  It  will  be  simpler  to  turn  the  weight  into  grains 
before  starting,  as  the  division  is  less  cumbersome. 

Another  way  is  to  find  how  many  times  the  escape  wheel 
revolves  to  one  turn  of  the  barrel  and  divide  the  weisrht 


THE    MODERN    CLOCK.  267 

by  that  number,  which  will  give  the  proportion  of  weight 
at  the  escape  wheel,  or  rather  would  do  so  if  there  were  no 
power  lost  by  friction.  It  is  usual  to  estimate  that  three- 
quarters  of  the  power  is  used  up  in  frictions  of  teeth  and 
pivots,  so  that  the  amount  actually  used  for  propulsion  of 
the  pendulum  is  very  small,  being  merely  sufficient  to  over- 
come the  bending  moment  of  the  suspension  spring  and  the 
resistance  of  the  air. 

It  is  for  this  reason  that  clocks  with  finely  cut  trains  and 
jeweled  pivots,  thus  having  little  train  friction,  will  run 
with  very  small  weights.  The  writer  knows  of  a  Howard 
regulator  with  jeweled  pivots  and  pallets  running  a  14- 
pound  pendulum  with  a  five-ounce  driving  weight.  Of 
course  this  is  an  extreme  instance  and  was  the  result  of  an 
experiment  by  an  expert  watchmaker  who  wanted  to  see 
what  he  could  do  in  this  direction. 

Usually  the  method  adopted  to  determine  the  amount  of 
weight  that  is  necessary  for  a  movement  is  to  hang  a  small 
tin  pail  on  the  weight  cord  and  fill  it  with  shot  sufficient  to 
barely  make  the  clock  keep  time.  When  this  point  has  been 
determined,  then  weigh  the  pail  of  shot  and  make  your  driv- 
ing weight  from  eight  to  sixteen  ounces  heavier.  In  doing 
this  be  sure  the  clock  is  in  beat  and  that  it  is  the  lack  of 
power  which  stops  the  clock ;  the  latter  point  can  be  readily 
determined  by  adding  or  taking  out  shot  from  the  pail  until 
the  amount  of  weight  is  determined.  The  extra  weight  is 
then  added  as  a  reserve  power,  to  counteract  the  increase 
of  friction  produced  by  the  thickening  of  the  oil. 

Many  clock  barrels  have  spiral  grooves  turned  in  them 
to  assist  in  keeping  the  coils  from  riding  on  each  other,  as 
where  such  riding  occurs  the  riding  coils  are  farther  from 
the  center  of  the  barrel  than  the  others,  which  gives  them  a 
longer  leverage  and  greater  power  while  they  are  unwinding, 
so  that  the  power  thus  becomes  irregular  and  affects  the  rate 
of  the  clock,  slowing  it  if  the  escapement  is  dead  beat  and 
making  it  go  faster  if  it  is  a  recoil  escapement. 


268  THE    MODERN    CLOCK. 

Clock  cords  should  be  attached  to  the  barrel  at  the  end 
which  is  the  farthest  from  the  pendulum,  so  that  as  they  un- 
wind the  weight  is  carried  away  from  the  pendulum.  This 
is  done  to  avoid  sympathetic  vibrations  of  the  weight  as  it 
passes  the  pendulum,  which  interfere  with  the  timekeeping 
when  they  occur.  If  the  weight  cannot  be  brought  far 
enough  away  to  avoid  vibrations  a  sheet  of  glass  may  be 
drilled  at  its  four  corners  and  fixed  with  screws  to  posts 
placed  in  the  back  of  the  case  at  the  point  where  vibration 
occurs,  so  that  the  glass  is  between  the  pendulum  rod  and 
the  weight,  but  does  not  interfere  with  either.  This  looks 
well  and  cures  the  trouble. 

We  have,  heretofore,  been  speaking  of  weights  which 
hang  directly  from  the  barrel,  as  was  the  case  with  the  older 
clocks  with  long  cases,  so  that  the  weight  had  plenty  of 
room  to  fall.  Where  the  cases  are  too  short  to  allow  of  this 
method,  recourse  is  had  to  hanging  the  weight  on  a  pulley 
and  fastening  one  end  of  the  cord  to  the  seat  board.  This 
involves  doubling  the  amount  of  weight  and  also  taking 
care  that  the  end  of  the  cord  is  fastened  far  enough  from 
the  slot  through  which  it  unwinds  so  that  the  cords  will 
not  twist,  as  they  are  likely  to  do  if  they  are  near  together 
and  the  cord  has  been  twisted  too  much  while  putting  it  on 
the  barrel.  Twisting  weight  cords  are  a  frequent  source  of 
trouble  when  new  cords  have  been  put  on  a  clock.  The 
pulley  is  another  source  of  trouble,  especially  if  wire  cords 
(picture  cords)  or  cables  are  used.  Wire  cable  should  not 
be  bent  in  a  circle  smaller  than  forty  times  its  diameter  if 
flexibility  is  to  be  maintained,  hence  pulleys  which  were  all 
right  for  gut  or  silk  frequently  prove  too  small  when  wire 
is  substituted  and  kinks,  twisted  and  broken  cables  frequent- 
ly result  from  this  cause.  This  is  especially  the  case  with 
the  heavy  weight  of  striking  trains  of  hall  and  chiming 
clocks,  where  double  pulleys  are  used,  and  also  leads  to 
trouble  by  jamming  and  cutting  the  cables  and  dropping 
of  the  weights  in  tower  clocks  where  a  new  cable  of  larger 


THE    MODERN    CLOCK.  269 

size  is  used  to  replace  an  old  one  which  has  become  unsafe 
from  rust,  or  cut  by  the  sheaves. 

Weight  cords  on  the  striking  side  of  a  clock  should  al- 
ways be  left  long  enough  so  that  they  will  not  run  down 
and  stop  before  the  time  train  has  stopped.  This  is  particu- 
larly the  case  with  the  old  English  hall  clocks,  as  many  of 
them  will  drop  or  push  their  gathering  racks  free  of  the 
gathering  pinion  under  such  conditions  and  then  when  the 
clock  is  wound  it  will  go  on  striking  continuously  until  the 
dial  is  taken  off  and  the  rack  replaced  in  mesh  with  the  gath- 
ering pinion.  As  clocks  are  usually  wound  at  night,  the 
watchmaker  can  see  the  disturbance  that  would  be  caused 
in  a  house  in  the  "wee  sma'  hours"  by  such  a  clock  going 
on  a  rampage  and  striking  continuously. 

Oiling  Cables.- — Clock  cables,  if  of  wire  and  small  in 
size,  should  be  oiled  by  dipping  in  vaseline  thinned  with 
benzine  of  good  quality.  Both  benzine  and  vaseline  must 
be  free  from  acid,  as  if  the  latter  is  present  it  will  attack  the 
cable.  This  thinning  will  permit  the  vaseline  to  permeate 
the  entire  cable  and  when  the  benzine  evaporates  it  will 
leave  a  thin  film  of  vaseline  over  every  wire,  thus  prevent- 
ing rust.  Tower  clock  cables  should  be  oiled  with  a  good 
mineral  oil,  well  soaked  into  them  to  prevent  rusting.  Gut 
clock  cords,  when  dry  and  hard,  are  best  treated  with  clock 
oil,  but  olive  oil  or  sperm  oil  will  also  be  found  good  to 
.soften  and  preserve  them.  New  cords  should  always  be 
oiled  until  they  are  soft  and  flexible.  If  the  weight  is  under 
ten  pounds  silk  cords  are  preferable  to  gut  or  wire  as  they 
are  very  soft  and  flexible. 

In  putting  on  a  new  cable  or  weight  cord  the  course  of 
the  weight  and  cord  should  be  closely  watched  at  all  points, 
to  see  that  they  remain  free  and  do  not  chafe  or  bind  any- 
w^here  and  also  that  the  coils  run  evenly  and  freely,  side  by 
side ;  sometimes,  especially  with  wire,  a  new  cable  gets 
kinked  by  riding^  the  first  time  of  winding:  and  is  then  very 


270  THE    MODERN    CLOCK. 

difficult  to  cure  of  this  serious  fault.  Another  point  to 
watch  is  to  see  that  the  position  of  the  cord  when  wound  up 
will  not  cause  an  end  thrust  upon  the  barrel,  which  will  in- 
terfere with  the  time  keeping  if  it  is  overwound,  so  that  the 
weight  is  jammed  against  the  seatboard;  this  frequently 
happens  with  careless  winding,  if  there  is  no  stop  work. 

To  determine  the  lengths  of  clock  cords  or  weights,  we 
may  have  to  approach  the  question  from  either  end.  If 
the  clock  be  brought  in  without  the  cords,  we  first  count 
the  number  of  turns  we  can  get  on  the  barrel.  This  may  be 
done  by  measuring  the  length  of  the  barrel  and  dividing  it 
by  the  thickness  of  the  cord,  if  the  barrel  is  smooth,  or  by 
counting  the  grooves  if  it  be  a  grooved  barrel.  Next  we 
caliper  the  diameter  and  add  the  thickness  of  one  cord,  which 
gives  us  the  diameter  of  the  barrel  to  the  center  of  the 
cords,  which  is  the  real  or  working  diameter.  Multiply  the 
distance  so  found  by  3. 141 56,  which  gives  the  circumference 
of  the  barrel,  or  the  length  of  cord  for  one  turn  of  the  bar- 
rel. Multiply  the  length  of  one  turn  by  the  number  of  turns 
and  we  have  the  length  of  cord  on  the  barrel,  when  it  is 
fully  wound.  If  the  cord  is  to  be  attached  to  the  weight, 
measure  the  distance  from  the  center  of  barrel  to  the  bottom 
of  the  seat  board  and  leave  enough  for  tieing.  If  the  weight 
is  on  a  pulley  it  will  generally  require  about  twelve  inches 
to  reach  from  the  barrel  through  the  slot  of  the  seat  board, 
through  the  pulley  to  the  point  of  fastening. 

To  get  the  fall  of  the  weight,  stand  it  on  the  bottom  of 
the  case  and  measure  the  distance  .from  the  top  of  the 
point  of  attachment  to  the  bottom  of  the  seat  board.  This 
will  generally  allow  the  weight  to  fall  within  two  inches  of 
the  bottom  and  thus  keep  the  cable  tight  when  the  clock  runs 
down;  thus  avoiding  kinks  and  over-riding  when  we  wind 
again  after  allowing  the  clock  to  run  down.  If  the  weight 
has  a  pulley  and  double  cord,  measure  from  the  top  of  the 
pulley  to  the  seatboard,  with  the  weight  on  the  bottom,  and 
then  double  this  measurement  for  the  length  of  the  cord. 


THE    MODERN    CLOCK. 


71 


This  measure  is  multiplied  by  as  many  times  as  there  are 
pulleys  in  the  case  of  additional  sheaves.  Striking  trains 
are  frequently  run  with  two  coils  or  layers  of  cord,  on  the 
barrel,  time  trains  never  have  but  one. 

Now,  having  the  greatest  available  length  of  cord  deter- 
mined according  either  of  the  above  conditions,  we  can  de- 
termine the  number  of  turns  for  which  we  have  room  on 
our  barrel  and  divide  the  length  of  cord  by  the  number  of 
turns.  This  will  give  us  the  length  of  one  turn  of  the  cord 
on  our  barrel  and  thus  having  found  the  circumference  it  is 
easy  to  find  the  diameter  which  we  must  give  our  barrel  in 
suiting  a  movement  to  given  dimensions  of  the  case.  This 
is  frequently  done  where  the  factory  may  want  a  movement 
to  fit  a  particular  style  and  size  of  case  which  has  proved 
popular,  or  when  a  watchmaker  desires  to  make  a  movement 
for  which  he  has,  or  will  buy,  a  case  already  made. 

As  to  tower  clock  cables,  getting  the  length  of  cable  on 
the  barrel  is,  of  course,  the  same  as  given  above,  but  the 
rest  of  it  is  an  individual  problem  in  every  case,  as  cables 
are  led  so  differently  and  the  length  of  fall  varies  so  that 
only  the  professional  tower  clock  men  are  fitted  to  make 
the  measurements  for  new  work  and  they  require  no  in- 
struction from  me.  It  might  be  well  to  add,  however,  that 
in  the  tower  clocks  by  far  the  greater  part  of  the  cable  is 
always  outside  the  clock  and  only  the  inner  end  coils  and 
uncoils  about  the  barrel.  It  is  for  this  reason  that  the  outer 
ends  of  the  cables  are  so  generally  neglected  by  watchmakeri' 
in  charge  of  tower  clocks  and  allowed  to  cut  and  rust  until 
they  drop  their  weights.  Caretakers  of  tower  clocks  should 
remember  that  the  inner  ends  of  cables  are  always  the  best 
ends ;  the  parts  that  need  watching  are  those  in  the  sheaves 
or  leading  to  the  sheaves.  Tower  clocks  should  have  the 
cables  marked  where  to  stop  to  prevent  overwinding. 

In  chain  drives  for  the  weights  of  cuckoo  and  other  clocks 
with  exposed  weights,  we  have  generally  a  steel  sprocket 
wheel   with   convex   guiding   surfaces   each    side    of    the 


272  THE    MODERN    CLOCK. 

sprocket  and  projecting  flanges  each  side  of  the  guides;  one 
of  these  flanges  is  generally  the  ratchet  wheel.  The  ratchet 
wheel,  guide,  sprocket,  guide  and  flange,  form  a  built-up 
wheel  which  is  loose  on  the  arbor  and  is  pinned  close  to  the 
great  wheel,  which  is  driven  by  a  click  on  the  wheel  working 
into  the  ratchet  of  the  drive.  It  must  be  loose  on  the  arbor, 
because  the  clock  is  wound  by  pulling  the  sprocket  and 
ratchet  backward  by  means  of  the  chain  until  the  weight  is 
raised  clear  up  to  the  seat  board.  There  are  no  squares  on 
the  arbors,  w^hich  have  ordinary  pivots  at  both  ends,  and 
the  great  wheel  is  fast  on  the  arbor.  The  diameter  of  the 
convex  portion  of  the  wheel  each  side  of  the  sprocket  is  the 
diameter  of  the  barrel,  and  the  chain  should  fit  so  that  alter- 
nate links  will  fit  nicely  in  the  teeth  of  the  sprocket ;  where 
this  is  not  the  case  they  will  miss  a  link  occasionally  and  the 
weight  will  then  fall  until  the  chain  catches  again,  when  it 
will  stop  with  a  jerk;  bent  or  jammed  links  in  the  chain  will 
do  the  sam?i  thing.  Sometimes  a  light  chain  on  a  heavy 
weight  will  stretch  or  spread  the  links  enough  to  make  their 
action  faulty.  If  examination  shows  a  tendency  to  open  the 
links,  they  should  be  soldered;  if  they  are  stretching,  a 
heavier  chain  of  correct  lengths  of  links  should  be  substi- 
tuted. Twisted  chains  are  another  characteristic  fault  and 
are  usually  the  result  of  bent  or  jammed  links.  A  close 
examination  of  such  a  chain  will  generally  reveal  several 
links  in  succession  which  are  not  quite  flat  and  careful 
straightening  of  these  links  will  generally  cure  the  tendency 
to  twist. 

Mainsprings  for  Clocks. — There  are  many  points  of 
difference  between  mainsprings  for  clocks  and  those  for 
watches.  They  differ  in  size,  strength,  number  of  coils  and 
in  their  eflfect  on  the  rates  of  the  clock. 

Watch  springs  are  practically  all  for  30-hour  lever  es- 
capements, with  a  few  cylinder,  duplex  and  chronometer 
escapements.     If  a  fusee  watch  happens  into  a  shop  nowa- 


THE    MODERN    CLOCK. 


273 


days  it  is  so  rare  as  to  be  a  curiosity  worth  stopping  work 
to  look  at. 

The  clocks  range  all  the  way  from  30  hours  to  400  days  in 
length  of  time  between  windings  and  include  lever,  cylinder, 
duplex,  dead  beat,  half  dead  beat,  recoil  and  other  escape- 
ments. Furthermore  some  of  these,  even  of  the  same  form 
of  escapements,  will  vary  so  in  weight  and  the  consequent 
influence  of  the  spring  that  what  will  pass  in  one  case  will 
give  a  wildly  erratic  rate  in  another  instance.  Many  of  the 
small  French  clocks  have  such  small  and  light  pendulums 
that  very  nice  management  of  the  stop  works  is  necessary 
to  prevent  the  clock  from  gaining  wildly  when  wound  or 
stopping  altogether  when  half  run  down. 

Nothing  will  cause  a  clock  with  a  cylinder  escapement 
to  vary  in  time  more  than  a  set  or  gummy  m.ainspring,  for 
it  will  gain  time  when  first  wound  and  lose  when  half  run 
down,  or  when  there  is  but  little  power  on  the  train.  In 
such  a  case  examine  the  mainspring  and  see  that  it  is  neither 
gummy  nor  set.  If  it  is  set,  put  in  a  new  spring  and  you  can 
probably  bring  it  to  time. 

With  a  clock  it  depends  entirely  on  the  kind  of  escape- 
ment that  it  contains,  w^hether  it  runs  fastei  or  slower,  with 
a  stronger  spring;  if  you  put  a  stronger  mainspring  in  a 
clock  that  contains  a  recoil  escapement  the  clock  will  gain 
time,  because  the  extra  power,  transmitted  to  the  pallets  will 
cause  the  pendulum  to  take  a  shorter  arc,  therefore  gain 
time,  where  the  reverse  occurs  in  the  dead-beat  escapement. 
A  stronger  spring  will  cause  the  dead-beat  pendulum  to  take 
a  longer  arc  and  therefore  lose  time. 

If  a  pendulum  is  short  and  light  these  effects  will  be  much 
greater  than  with  a  long  and  heavy  pendulum. 

At  all  clock  factories  they  test  the  mainsprings  for  power 
and  to  see  that  they  unwind  evenly ;  those  that  do  are  marked 
No.  I,  and  those  that  do  not  are  called  ''seconds."  The  sec- 
onds are  used  only  for  the  striking  side  of  the  clocks,  while 
the  perfect  ones  are  used   for  the  running,   or  time  side. 


274 


THE    MODERN    CLOCK. 


Sometimes,  however,  a  seconds'  spring  will  be  put  on  the 
time  side  and  will  cause  the  clock  to  vary  in  a  most  erratic 
way.  This  changing  of  springs  is  very  often  done  by  care- 
less or  ignorant  workmen  in  cleaning  and  then  they  cannot 
locate  the  trouble. 

All  mainsprings  for  both  clocks  and  watches  should  be 
smooth  and  well  polished.  Proper  attention  to  this  one  item 
will  save  many  dollars'  worth  of  time  in  examining  move- 
ments to  try  to  detect  the  cause  of  variations. 

A  rough  mainspring  (that  is,  an  emery  finished  main- 
spring) will  lose  one-third  of  its  power  from  coil  friction, 
and  in  certain  instances  even  one-half.  The  deceptive  fea- 
ture about  this  to  the  watchmaker  is  that  the  clock  will  take 
a  good  motion  with  a  rough  spring  fully  found,  but  v/ill  fall 
off  when  partly  unwound,  and  the  consequence  is  that  he 
finds  a  good  motion  when  the  spring  is  put  in  and  w^ound, 
and  he  afterward  neglects  to  examine  the  spring  w^hen  he 
examines  the  rate  as  faulty.  The  best  springs  are  cheap 
enough,  so  that  only  the  best  quality  should  be  used,  as  it 
is  easy  for  a  watchmaker  to  lose  three  or  four  dollars'  worth 
of  time  looking  for  faults  in  the  escapement,  train  and  ev- 
erywhere else,  except  the  barrel,  when  he  has  inserted  a 
rough,  thick,  poorly  made  spring.  The  most  that  he  can 
save  on  the  cheaper  qualities  of  springs  is  about  five  cents 
per  spring  and  we  will  ask  any  watchmaker  how  long  it 
would  take  to  lose  five  cents  in  examination  of  a  movement 
to  see  what  is  defective. 

Here  is  something  which  you  can  try  yourself  at  the 
bench.  Take  a  rough  watch  mainspring;  coil  it  small 
enough  to  be  grasped  in  the  hand  and  then  press  on  the 
spring  evenly  and  steadily.  You  will  find  it  difficult  to  make 
the  coils  slide  on  one  another  as  the  inner  coils  get  smaller ; 
they  will  stick  together  and  give  way  by  jerks.  Now  open 
your  hand  slowly  and  you  will  feel  the  spring  uncoiling  in 
an  abrupt,  jerky  way,  sometimes  exerting  very  little  pressure 
on  the  hand,  at  other  times  a  great  deal.     A  dirty,  gummy 


THE    MODERN    CLOCK. 


275 


spring  will  do  the  same  thing.  Now  take  a  clean,  well  pol- 
ished spring  and  try  it  the  same  way ;  notice  how  much  more 
even  and  steady  is  the  pressure  required  to  move  the  coils 
upon  each  other,  either  in  compressing  or  expanding.  Now 
oil  the  well  polished  spring  and  try  it  again.  You  will  find 
you  now  have  something  that  is  instantly  responding,  evenly 
and  smoothly,  to  every  variation  of  pressure.  You  can  also 
compress  the  spring  two  or  three  turns  farther  with  the 
same  force.  This  is  what  goes  on  in  the  barrel  of  every 
clock  or  watch;  you  have  merely  been  using  your  hand  as 
a  barrel  and  feeling  the  action  of  the  springs. 

Now  a  well  finished  mainspring  that  is  gummy  is  as  ir- 
regular in  its  action  as  the  worst  of  the  springs  described 
above,  yet  very  few  watchmakers  will  take  out  the  springs 
of  a  clock  if  they  are  in  a  barrel.  One  of  them  once  said  to 
me,  "Why,  who  ever  takes  out  springs?  I'll  bet  I  clean  a 
hundred  clocks  before  I  take  out  the  springs  of  one  of 
them!"  Yet  this  same  man  had  then  a  clock  which  had 
come  back  to  him  and  which  was  the  cause  of  the  conver- 
sation. 

There  must  be  in  this  country  over  25,000  fine  French 
clocks  in  expensive  marble  or  onyx  cases,  which  were  given 
as  wedding  presents  to  their  owners,  and  which  have  never 
run  properly  and  in  many  instances  cannot  be  made  to  run 
by  the  watchmakers  to  whom  they  were  taken  when  they 
stopped.  Let  me  give  the  history  of  one  of  them.  It  was  an 
eight-day  French  marble  clock  which  cost  $25  (wholesale) 
in  St.  Louis  and  was  given  as  a  wedding  present.  Three 
months  later  it  stopped  and  was  taken  to  a  watchmaker  well 
known  to  be  skillful  and  who  had  a  fine  run  of  expensive 
watches  constantly  coming  to  him.  He  cleaned  the  clock, 
took  it  home  and  it  ran  three  hours !  It  came  back  to  him 
three  times;  during  these  periods  he  went  over  the  move- 
ment repeatedly ;  every  wheel  was  tested  in  a  depthing  tool 
and  found  to  be  round :  all  the  teeth  were  examined  sepa- 
rately under  a  glass  and  found  to  be  perfect;  the  pinions 


276  T'lE    MODERN    CLOCK. 

were  subjected  to  the  same  careful  scrutiny;  the  depthings 
were  tried  with  each  wheel  and  pinion  separately ;  the  pivots 
were  tested  and  found  to  be  right;  the  movement  was  put 
in  its  case  and  examined  there;  it  would  run  all  right  on 
the  watchmaker's  bench/  but  not  in  the  home  of  its  owner. 
It  would  stop  every  time  it  was  moved  in  dusting  the  man- 
tel. He  became  disgusted  and  took  the  clock  to  another 
watchmaker,  a  railroad  time  inspector;  same  results.  In 
this  way  the  clock  moved  about  for  three  years ;  whenever 
the  owner  heard  of  a  man  who  was  accounted  more  than 
ordinarily  skillful  he  took  him  the  clock  and  watched  him 
''fall  down"  on  it.  Finally  it  came  into  the  hands  of  an 
ex-president  of  the  American  Horological  Society.  He 
made  it  run  three  weeks.  When  he  found  the  clock  had 
stopped  again  he  refused  pay  for  it.  Three  months  later  he 
called  and  got  the  clock,  kept  it  for  three  weeks,  brought  it 
back  without  explanation  and  lo,  the  clock  ran!  It  would 
even  run  considerably  out  of  beat!  When  asked  what  he 
had  done  to  the  clock,  he  merely  laughed  and  said  "Wait.'* 

A  year  later  the  clock  was  still  going  satisfactorily  and  he 
explained.  "That  was  the  first  time  I  ever  got  anything  I 
couldn't  fix  and  it  made  me  ashamed.  I  kept  thinking  it 
over.  Finally  one  night  in  bed  I  got  to  considering  why  a 
clock  wouldn't  run  when  there  was  nothing  the  matter  with 
it.  The  only  reason  I  could  see  was  lack  of  power.  Next 
morning  I  got  the  clock  and  put  in  new  mainsprings,  the  best 
I  could  find.  The  clock  was  cured !  None  of  these  other 
men  who  had  the  clock  took  out  the  springs.  They  came 
to  me  all  gummed  up,  while  the  rest  of  the  clock  was  clean, 
bright  and  in  perfect  order,  I  cleaned  the  springs  and  re- 
turned the  clock ;  it  ran  three  weeks.  When  I  took  it  back 
I  put  in  stronger  springs,  because  I  found  them  a  little  soft 
on  testing  them.  If  any  of  your  friends  have  French  clocks 
that  won't  go,  send  them  to  me." 

Three-quarters  of  the  trouble  with  French  clocks  is  in 
the  spring  box;  mainspring  too  weak,  gummy  or  set;  stop 


THE    MODERN    CLOCK.  277 

works  not  properly  adjusted,  or  left  off  by  some  numskull 
who  thought  he  could  make  the  clock  keep  time  without  it 
when  the  maker  couldn't;  mainspring  rough,  so  that  it  un- 
coils by  jerks ;  spring  too  strong,  so  that  the  small  and  light 
pendulum  cannot  control  it.  These  will  account  for  far 
more  cases  than  the  ''flat  wheel"  story  that  so  often  comes 
to  the  front  to  account  for  a  failure  on  the  part  of  the  work- 
man. Of  course  he  must  say  something  to  his  boss  to  ac- 
count for  his  failure  and  the  ''wheels  out  of  round"  and 
*'.the  faulty  depthing"  have  been  standard  excuses  for  French 
clocks  for  a  century.  Of  course  they  do  occur,  but  not 
nearly  as  often  as  they  are  credited  with,  and  even  then  such 
a  clock  may  be  made  to  perform  creditably  if  the  springs 
are  right. 

Another  source  of  trouble  is  buckled  springs,  caused  by 
some  workman  taking  them  out  or  putting  them  in  the  bar- 
rel without  a  mainspring  winder.  There  are  many  men 
who  will  tell  you  that  they  never  use  a  winder;  they  can 
put  any  spring  in  without  it.  Perhaps  they  can,  but  there 
comes  a  day  when  they  get  a  soft  spring  that  is  too  wide  for 
this  treatment  and  they  stretch  one  side  of  it,  or  bend,  or 
kink  it,  and  then  comes  coil  friction  with  its  attendant  evils. 
These  may  not  show  with  a  heavy  pendulum,  but  they  are 
certain  to  do  so  if  it  happens  to  be  an  eight-day  movement 
with  light  pendulum  or  balance,  and  this  is  particularly  true 
of  a  cylinder. 

All  springs  should  be  cleaned  by  soaking  in  benzine  or 
gasoHne  and  rubbing  with  a  rag  until  all  the  gum  is  ofi^ 
them  before  they  are  oiled.  Heavy  springs  may  be  wiped 
by  wrapping  one  or  two  turns  of  a  rag  around  them  and 
pushing  it  around  the  coils.  The  spring  should  be  well 
cleaned  and  dried  before  oiling.  A  quick  way  of  cleaning 
is  to  wind  the  springs  clear  up;  stick  a  peg  in  the  escape 
wheel ;  remove  the  pallet  fork ;  plunge  the  whole  movement 
into  a  pail  of  gasoline  large  enough  to  cover  it ;  let  it  stand 
until  the  gasoline  has  soaked  into  the  barrels;  remove  the 


278  THE    MODERN    CLOCK. 

peg  and  let  the  trains  run  down.  The  coils  of  the  spring 
will  scrub  each  other  in  unwinding;  the  pivots  will  clean 
the  pivot  holes  and  the  teeth  of  wheels  and  pinions  will  clean 
each  other.  Then  take  the  clock  apart  for  repairs.  Springs 
which  are  not  in  barrels  should  be  wound  up  and  spring 
clamps  put  on  them  before  taking  down  the  clock.  About 
six  sizes  of  these  clamps  (from  2^  inches  to  ^  inch)  are 
sufficient  for  ordinary  work. 

Rancid  oilis  also  the  cause  of  many  "come-backs."  Work- 
men will  buy  a  large  bottle  of  good  oil  and  leave  it  standing 
uncorked,  or  in  the  sun,  or  too  near  a  stove  in  winter  time, 
until  it  spoils.  Used  in  this  condition  it  will  dry  or  gum  in 
a  month  or  two  and  the  clock  comes  back,  if  the  owner  is 
particular;  if  not,  he  simply  tells  his  friends  that  you  can't 
fix  a  clock  and  they  had  better  go  elsewhere  with  their 
watches. 

For  clock  mainsprings,  clock  oil,  such  as  you  buy  from 
material  dealers,  is  recommended,  provided  it  is  intended 
for  French  mainsprings.  If  the  "lubricant  is  needed  for 
coarse  American  springs,  mix  some  vaseline  with  refined 
benzine  and  put  it  .on  hberally.  The  benzine  will  dissolve 
the  vaseline  and  will  help  to  convey  the  lubricant  all  over 
the  spring,  leaving  no  part  untouched.  The  liquid  will  then 
evaporate,  leaving  a  thin  coating  of  vaseline  on  the  spring. 

It  is  best  to  let  springs  dow^n  with  a  key  made  for  the 
purpose.  It  is  a  key  with  a  large,  round,  wooden  handle, 
which  fills  the  hand  of  the  watchmaker  when  he  grasps  it. 
Placing  the  key  on  the  arbor  square,  with  the  movement 
►held  securely  in  a  vise,  wind  the  spring  until  you  can  "re- 
lease the  click  of  the  ratchet  with  a  screwdriver,  wire  or 
other  tool;  hold  the  click  free  of  the  ratchet  and  let  the 
handle  of  the  key  turn  slowly  round  in  the  hand  until  the 
spring  is  down.  Be  careful  not  to  release  the  pressure  on 
the  key  too  much,  or  it  will  get  away  from  you  if  the  spring 
is  strong,  and  will  damage  the  movement.  This  is  why  the 
handle  is  made  so  large,  so  that  you  can  hold  a  strong 
spring. 


THE    MODERN    CLOCK.  279 

It  is  of  great  importance,  if  we  wish  to  avoid  variable 
coil  friction,  that  the  spring  should  wind,  from  the  very 
starting,  concentrically ;  i.  e.,  that  the  coils  should  commence 
to  wind  in  regular  spirals,  equidistant  from  each  other, 
around  the  arbor.  In  very  many  cases  we  find,  when  we 
commence  to  wind  a  spring,  that  the  innermost  coil  bulges 
out  on  one  side,  causing,  from  the  very  beginning,  a  greater 
friction  of  the  coils  on  that  side,  the  outer  ones  pressing 
hard  against  it  as  you  continue  to  wind,  while  on  the  outer 
side  of  the  arbor  they  are  separated  from  each  other  by 
quite  a  little  space  betw^een  them,  and  that  this  bulge  in  the 
first  coil  is  overcome  and  becomes  concentric  to  the  arbor 
only  after  the  spring  is  more  than  half  way  wound  up.  Thia 
necessarily  produces  greater  and  more  variable  coil  friction. 
When  a  spring  is  put  into  the  barrel  the  innermost  coil 
should  come  to  the  center  around  the  arbor  by  a  gradual 
sweep,  starting  from  at  least  one  turn  around  away  irom 
the  other  coils.  Instead  of  that,  we  more  often  find  it  lay- 
ing close  to  the  outer  coils  to  the  very  end,  and  ending 
abruptly  in  the  curl  in  the  soft  end  that  is  to  be  next  the 
arbor.  When  this  is  the  case  in  a  spring  of  uniform  thick- 
ness throughout,  it  is  mainly  due  to  the  manner  of  first 
winding  it  from  its  straight  into  a  spiral  form.  To  obviate 
it,  I  generally  wind  the  first  coils,  say  tw^o  or  three,  on  a 
center  in  the  winder,  a  trifle  smaller  than  the  regular  one, 
which  is  to  be  of  the  same  diameter  of  the  arbor  center  in 
the  barrel.  You  will  find  that  the  substitution  of  the  regu- 
lar center,  afterwards,  will  not  undo  the  extra  bending  thus 
produced  on  the  inner  coils,  and  that  the  spring  will  abut 
by  a  more  gradual  sw^eep  at  the  center,  and  wind  more  con- 
centrically. 

The  form  of  spring  formerly  used  with  a  fusee  in  Eng- 
lish carriage  clocks  and  marine  chronometers  is  a  spring 
tapering  slightly  in  thickness  from  the  inner  end  for  a  dis- 
tance of  two  full  coils,  the  thickness  increasing  as  we  move 
away  from  the  end,  then  continuing  of  uniform  thickness 


28o  THE    MODERN    CLOCK. 

until  within  about  a  coil  and  a  half  from  the  other  end, 
when  it  again  increases  in  thickness  by  a  gradual  taper. 
The  increase  in  the  thickness  towards  the  outer  end  will 
cause  it  to  cling  more  firmly  to  the  wall  of  the  barrel.  The 
best  substitute  for  this  taper  on  the  outside  is  a  brace  added 
to  some  of  the  springs  immediately  back  of  the  hole.  With 
this  brace,  and  the  core  of  the  winding  arbor  cut  spirally, 
excellent  results  are  obtained  with  a  spring  of  uniform  thick- 
ness throughout  its  entire  length.  Something,  too,  can  be 
done  to  improve  the  action  of  a  spring  that  has  no  brace, 
l)y  hooking  it  properly  to  the  barrel.  The  hole  in  the  spring 
on  the  outside  should  never  be  made  close  to  the  end ;  on  the 
contrary,  there  should  be  from  a  half  to  three-quarters  of  an 
inch  left  beyond  the  hole.  This  end  portion  will  act  as  a 
brace. 

When  the  spring  is  down,  the  innermost  coil  of  it  should 
form  a  gradual  spiral  curve  towards  the  center,  so  as  to 
meet  the  arbor  without  forcing  it  to  one  side  or  the  other. 
This  curve  can  be  improved  upon,  if  not  correct,  with  suit- 
ably shaped  pliers;  or  it  can  be  approximated  by  winding 
the  innermost  coils  first  on  an  arbor  a  little  smaller  in  diam- 
eter than  the  barrel  arbor  itself. 

Another  and  very  important  factor  in  the  development  of 
the  force  of  the  spring  is  the  proper  length  and  thickness 
of  it.  For  any  diameter  of  barrel  there  is  but  one  length 
and  one  thickness  of  spring  that  will  give  the  maximum 
number  of  turns  to  wind.  This  is  conditioned  by  the  fact 
that  the  volume  w^hich  the  spring  occupies  when  it  is  down 
must  not  be  greater  nor  less  than  the  volume  of  the  empty 
space  around  the  arbor  into  which  it  is  to  be  wound,  so  that 
the  outermost  coil  of  the  spring  when  fully  wound  will  oc- 
cupy the  same  place  which  the  innermost  occupies  when  it 
is  down.  In  a  barrel,  the  diameter  of  whose  arbor  is  one- 
third  that  of  the  barrel,  the  condition  is  fulfilled  when  the 
measure  across  the  coils  of  the  spring  as  it  lays  against  the 
wall  of  the  barrel,  is  0.39  of  the  empty  space,  or,  taking  the 


THE    MODERN    CLOCK.  281 

diameter  of  the  barrel  as  a  comparison,  0.123  of  the  latter; 
in  other  words,  nearly  one-eighth  of  the  diameter  of  the 
barrel.  This  is  the  width  that  will  give  the  greatest  number 
of  turns  to  wind,  whatever  may  be  the  length  or  thickness 
of  any  spring.  If  now  we  desire  a  spring  to  wind  a  given 
number  of  turns,  there  is  but  one  thickness  and  one  length 
of  it  that  will  permit  it  to  do  so.  The  thickness  remaining 
the  same,  if  we  make  the  spring  longer  or  shorter,  we  re- 
duce the  number  of  turns  it  will  wind;  more  rapidly  by 
making  it  shorter,  less  so  by  making  it  longer.  It  is  there- 
fore not  only  useless,  but  detrimental,  to  put  into  a  barrel 
a  greater  number  of  coils,  or  turns,  than  are  necessary,  not 
only  because  it  will  reduce  the  number  of  turns  the  barrel 
will  wind,  but  it  will  produce  greater  coil  friction  by  filling 
up  the  space  with  more  coils  than  are  necessary. 

A  mainspring  in  the  act  of  uncoiling  in  its  barrel  always 
gives  a  number  of  turns  equal  to  the  difference  between  the 
number  of  coils  in  the  up  and  the  down  positions.  Thus,  if 
17  be  the  number  of  coils  when  the  spring  is  run  down,  and 
25  the  number  when  against  the  arbor,  the  number  of  turns 
in  uncoiling  will  be  8,  or  the  difference  between  17  and  2^. 

The  cause  of  breakage  is  usually,  that  the  inner  coils  are 
put  to  the  greatest  strain,  and  then  the  slightest  flaw  in  the 
steel,  a  speck  of  rust,  grooves  cut  in  the  edges  of  the  spring 
by  allowing  a  screwdriver  to  slip  over  them,  or  an  unequal 
effect  of  change  of  temperature,  causes  the  fracture,  and 
leaves  the  spring  free  to  uncoil  itself  with  verv  great  rapid- 
ity. 

Now  this  sudden  uncoiling  means  that  the  whole  energy 
of  the  spring  is  expended  on  the  barrel  in  a  very  small  frac- 
tion of  a  second.  In  reality  the  spring  strikes  the  inner  side 
of  the  rim  of  the  barrel,  a  violent  blow  in  the  direction  the 
spring  is  turning,  that  is,  backwards ;  this  is  due  to  the 
mainspring's  inertia  and  its  very  high  mean  velocity.  The 
velocity  is  nothing  at  the  outer  end,  where  the  spring  is 
fixed,  but  rises  to  the  maximum  at  the  point  of  fracture,  and 


282  THE    MODERN    CLOCK. 

the  kinetic  energy  at  various  points  of  the  spring  could  no 
doubt  be  calculated  mathematically  or  otherwise. 

For  instance,  take  a  going  barrel  spring  of  eight  and  a 
half  turns,  breaking  close  up  to  the  center  while  fully  wound. 
A 'point  in  the  spring  at  the  fracture  makes  eight  turns  in 
the  opposite  direction  to  which  it  was  wound,  a  point  at  the 
middle  four  turns,  and  a  point  at  the  outer  end  nothing,  an 
effect  similar  to  the  whole  mass  of  the  spring  making  four 
turns  backwards.  At  its  greatest  velocity  it  is  suddenly 
stopped  by  the  barrel,  wheel  teeth  engaging  its  pinion;  this 
stoppage  or  collision  is  what  breaks  center  pinions,  third  piv- 
ots, wheel  teeth,  etc.,  unless  their  elasticity,  or  some  inter- 
posed contrivance,  can  safely  absorb  the  stored-up  energy 
of  the  mainspring,  the  spring  being,  as  every  one  knows, 
the  heaviest  moving  part  in  an  ordinary  clock,  except  where 
the  barrel  is  exceptionally  massive. 

Stop  Works. — Stop  works  are  devices  that  are  but  little 
understood  by  the  majority  of  workmen  in  the  trade.  They 
are  added  to  a  movement  for  either  one  or  both  of  two  dis- 
tinct purposes:  First,  as  a  safety  device,  to  prevent  injury 
to  the  escape  wheel  from  over  winding,  or  to  prevent  undue 
force  coming  on  the  pendulum  by  jamming  the  weight 
against  the  top  of  the  seat  board  and  causing  a  variation  in 
time  in  a  fine  clock;  or,  second,  to  use  as  a  compromise  by 
utilizing  only  the  middle  portion  of  a  long  and  powerful 
spring,  which  varies  too  much  in  the  amount  of  its  power 
in  the  up  and  down  positions  to  get  a  good  rate  on  the 
clock  if  all  the  force  of  the  spring  were  utilized  in  driv- 
ing the  movement. 

With  weight  clocks,  the  stop  work  is  a  safety  device  and 
should  always  be  set  so  that  it  will  stop  the  winding  when 
the  barrel  is  filled  by  the  cord ;  consequently  the  way  to  set 
them  is  to  wind  until  the  barrel  is  barely  full  and  set  the 
stops  with  the  fingers  locked  so  as  to  prevent  any  further 
action  of  the  arbor  in  the  direction  of  the  windincr  and  the 


THE    MODERN    CLOCK.  283 

cord  should  then  be  long  enough  to  permit  the  weight  to  be 
free.  Then  unwind  until  within  half  a  coil  of  the  knot  in 
the  cord  where  it  is  attached  to  the  barrel  and  see  that  the 
weight  is  also  free  at  the  bottom  of  the  case,  when  the  stops 
again  come  into  action.  This  will  allow  the  full  capacity 
of  the  barrel  to  be  used. 

When  stop  work  is  found  on  a  spring  barrel,  it  may  be 
taken  for  granted  that  the  barrel  contains  more  spring  than 
is  being  wound  and  unwound  in  the  operation  of  the  clock 
and  it  then  becomes  important  to  know  how  many  coils  are 
thus  held  under  tension,  so  that  wc  may  put  it  back  .cor- 
rectly after  cleaning.  Wind  up  the  spring  and  then  let  it 
slowly  down  with  the  key  until  the  stop  work  is  locked, 
counting  the  number  of  turns,  and  writing  it  down.  Then 
hold  the  spring  with  the  letting  down  key  and  take  a  screw 
driver  and  remove  the  stop  from  the  plate ;  then  count  the 
number  of  turns  until  the  spring  is  down  and  also  write 
that  down.  Then  take  out  the  spring  and  clean  it.  You 
may  find  such  a  spring  will  give  seventeen  turns  in  the  bar- 
rel without  the  stop  work  on,  while  it  will  give  but  ten  with 
the  stop  work;  also  that  the  arbor  turned  four  revolutions 
after  you  removed  the  stop.  Then  the  spring  ran  the  clock 
from  the  fourth  to  the  fourteenth  turns  and  there  were 
four  coils  unused  around  the  arbor,  ten  to  run  the  clock  and 
three  unused  at  the  outer  end  around  the  barrel.  This 
would  indicate  a  short  and  light  pendulum  or  balance,  which 
is  very  apt  to  be  erratic  under  variations  of  power,  and  if 
the  rate  was  complained  of  by  the  customer  you  can  look 
for  trouble  unless  the  best  adjustment  of  the  spring  is  se- 
cured. Put  the  spring  back  by  winding  the  four  turns  and 
putting  on  the  stop  work  in  the  locked  position ;  then  wind. 
If  the  clock  gains  when  up  and  loses  when  down,  shift  the 
stop  works  half  a  turn  backwards  or  forwards  and  note  the 
result,  making  changes  of  the  stop  until  you  have  found 
the  point  at  which  there  is  the  least  variation  of  power  in 
the  up  and  down  positions.  If  the  variation  is  still  too  great 
a  thinner  spring  must  be  substituted. 


284  THE    MODERN    CLOCK. 

There  are  several  kinds  of  stop  work,  the  most  common 
being  what  is  known  as  the  Geneva  stop,  a  Maltese  cross 
and  a  finger  such  as  is  commonly  seen  on  watches.  For 
watches  they  have  five  notches,  but  for  clocks  they  are 
made  with  a  greater  number  of  notches,  according  to  the 
number  of  turns  desired  for  the  arbor.  The  finger  piece  is 
mounted  on  a  square  on  the  barrel  arbor  and  the  star  wheel 
on  the  stud  on  the  plate.  In  setting  them  see  that  the  finger 
is  in  line  with  the  center  of  the  star  wheel  when  the  stop  is 
locked,  or  they  will  not  work  smoothly. 

There  is  another  kind  of  stop  work  which  is  used  in  some 
American  clocks,  and  as  there  is  no  friction  with  it,  and  no 
fear  of  sticking,  nor  any  doubt  of  the  certainty  of  its  action, 
it  is  perhaps  the  most  suitable  for  regulators  and  other  fine 
clocks  which  have  many  turns  of  the  barrel  in  winding. 
This  stop  is  simple  and  sure.  It  consists  of  a  pair  of  wheels 
of  any  numbers  with  the  ratio  of  odd  numbers  as  7  and  6, 
9  and  10,  15  and  16,  30  and  32,  45  and  48,  etc. ;  the  smaller 
wheel  is  squared  on  the  barrel  arbor  and  the  larger  mounted 
on  a  stud  on  the  plate.  These  wheels  are  better  if  made 
with  a  larger  number  of  teeth.  On  each  wheel  a  finger  is 
planted,  projecting  a  little  beyond  the  outsides  of  the  wheel 
teeth,  so  that  when  the  fingers  meet  they  will  butt  securely. 
The  meeting  of  these  fingers  cannot  take  place  at  every 
revolution  because  of  the  difference  in  the  numbers  of  the 
teeth  of  the  wheels ;  they  will  pass  without  touching  every 
time  till  the  cycle  of  turns  is  completed,  as  one  wheel  goes 
round  say  sixteen  times  while  the  other  goes  fifteen,  and 
when  this  occurs  the  fingers  will  engage  and  so  stop  fur- 
ther winding.  When  the  clock  has  run  down  sixteen  turns 
of  the  barrel  the  fingers  will .  again  meet  on  the  opposite 
side,  and  so  the  barrel  will  be  allowed  to  turn  backwards 
and  forwards  for  sixteen  revolutions,  being  stopped  by  the 
fingers  at  each  extreme.  When  in  action  the  fingers  may 
butt  either  at  a  right  or  an  obtuse  angle,  only  not  too  obtuse, 
as  this  would  put  a  strain  on,  tending  to  force  the  wheels 


THE    MODERN    CLOCK. 


apart.     If  preferred  the  fingers  may  be  made  of  steel,  but 
this  is  not  necessary. 

Maintaining  Powers. — x\stronomical  clocks,  watch- 
maker's regulators  and  tower  clocks  arc,  or  at  least  should 
be,  fitted  with  maintaining  power.  A  good  tower  clock 
should  not  vary  in  its  rate  more  than  five  to  ten  seconds  a 
week.  Many  of  them,  when  favorably  situated  and  care- 
fully tended,  do  not  vary  over  five  to  ten  seconds  per  month. 
It  requires  from  five  to  thirty  minutes  to  wind  the  time 
trains  of  these  clocks  and  the  reader  can  easily  see  where 


Fig.  83 

the  rate  would  go  if  the  power  were  removed  from  the  pen- 
dulum for  that  length  of  time ;  hence  a  maintaining  power 
that  will  keep  nearly  the  same  pressure  on  the  escape  wheel 
as  the  weight  does,  is  a  necessity.  Astronomical  clocks  and 
fine  regulators  have  so  little  train  friction,  especially  if  jew- 
eled, that  when  the  barrel  is  turned  backwards  in  winding 
the  friction  between  the  barrel  head  and  the  gr^at  wheel  is 
sufficient  to  stop  the  train,  or  even  run  it  backwards,  injur- 
ing the  escape  wheel  and,  of  course,  destroying  the  rate  of 
the  clock;  therefore  they  are  provided  with  a  device  that 
will  prevent  such  an  occurrence.  Ordinary  clocks  do  not 
have  the  maintaining  power  because  only  the  barrel  arbor 
is  reversed  in  winding,  and  that  reversal  is  never  for  more 
than  half  a  turn  at  a  time,  as  the  power  is  thrown  back  on 
the  train  every  time  the  winder  lets  go  of  the  key  to  turn 
his  hand  over  for  another  grip. 


286 


THE    MODERN    CLOCK. 


Figs.  83,  84  and  85  show  the  various  forms  of  main- 
taining powers,  which  differ  only  in  their  mechanical  de- 
tails. In  all  of  them  the  maintaining  power  consists  of  two 
ratchet  wheels,  two  clicks  and  either  one  or  two  springs ; 
the  springs  vary  in  shape  according  to  whether  the  great 
wheel  is  provided  with  spokes  or  left  with  a  web.  If  the 
great  wheel  has  spokes  the  springs  are  attached  on  the  out- 
side of  the  large  ratchet  wheel  so  that  they  will  press  on 
opposite  spokes  of  the  great  wheel  and  are  either  straight, 
curved  or  coiled,  according  to  the  taste  of  the  maker  of  the 
clock  and  the  amount  of  room.    If  made  with  a  web  a  cir- 


Fig.  84 


cular  recess  is  cut  in  the  great  wheel,  see  Fig.  83,  wide  and 
deep  enough  for  a  single  coil  of  spring  wire  which  has  its 
ends  bent  at  right  angles^  to  the  plane  of  the  spring  and  one 
end  slipped  in  a  hole  of  the  ratchet  and  the  other  in  a  sim- 
ilar hole  in  the  recess  of  the  great  wheel.  A  circular  slot 
is  cut  at  some  portion  of  the  recess  in  the  great  wheel 
where  it  will  not  interfere  with  the  spring  and  a  screw  in 
the  ratchet  works  back  and  forth  in  this  slot,  limiting  the 
action  of  the  spring.  Stops  are  also  provided  for  the  spokes 
of  the  great  wheel  in  the  case  of  straight,  curved  or  coiled 
springs,  Figs.  84  and  85.     These  stops  are  set  so  as  to  give 


THE    MODERN    CLOCK.  2S7 

an  angular  movement  of  two  or  three  teeth  of  the  great 
wheel  in  the  case  of  tower  clocks  and  from  six  to  eight 
teeth  in  a  regulator.  The  springs  should  exert  a  pressure 
on  the  great  wheel  of  just  a  little  less  than  the  pull  of  the 
weight  on  the  barrel ;  they  will  then  be  compressed  all  the 
time  the  weight  is  in  action,  and  the  stops  will  then  transmit 
the  power  from  the  large  ratchet  to  the  great  wheel,  which 
drives  the  train.  Both  the  great  wheel  and  the  large  rat- 
chet wheel  are  loose  on  the  arbor,  being  pinned  close  to  the 
barrel,  but  free  to  revolve.     A  smaller  ratchet,  having  its 


Fig.  85 

teeth  cut  in  the  reverse  direction  from  those  of  the  larger 
one,  is  fast  to  the  end  of  the  barrel.  A  click,  called  the 
winding  click,  on  the  larger  ratchet  acts  in  the  teeth  of  the 
smaller  one  during  the  winding,  holding  the  two  ratchets 
together  at  all  other  times.  A  longer  click,  called  the  de- 
tent click,  is  pivoted  to  the  clock  plate,  and  drags  idly  over 
the  teeth  of  the  larger  ratchet  while  the  clock  is  being 
driven  by  the  weight  and  the  maintaining  springs  are  com- 
pressed. When  the  power  is  taken  off  by  the  reversal  of 
the  barrel  in  winding,  the  friction  between  the  sides  of  the 
two  ratchets  and  great  wheel  would  cause  them  to  also  turn 
backward,  if  it  wevQ  not  for  this  detent  click.  W'ith  its  end 
fast  to  the  plate,  which  drops  into  the  teeth  of  the  large 
ratchet  and  prevents  it  from  turning  backward.  We  now 
have  the  large  ratchet  held  motionless  by  the  detent  click 
on  the  clock  plate  and  the  compressed  springs  which  are 


288 


THE    MODERN    CLOCK. 


carried  between  the  large  ratchet  and  the  great  wheel  will 
then  begin  to  expand,  driving  the  loose  great  wheel  until 
their  force  has  been  expended,  or  until  winding  is  com- 
pleted, when  they  will  again  be  compressed  by  the  pull  of 
th-e  weight.  In  some  tower  clocks  curved  pins  are  fixed  to 
opposite  spokes  of  the  great  wheel  and  coiled  springs  are 
wound  around  the  pins.  Fig.  85 ;  eyes  in  the  large  ratchet 
engage  the  outer  ends  of  the  pins  and  compress  the  springs. 
The  clicks  for  maintaining  powers  should  not  be  short, 
and  the  planting  should  be  done  so  that  lines  drawn  from 
the  barrel  center  to  the  click  points  and  from  the  click  cen- 
ters to  the  points,  will  form  an  obtuse  angle,  like  B,  Fig.  86. 


Fig. 


giving  a  tendency  for  the  ratchet  tooth  to  draw  the  click 
towards  the  barrel  center.  The  clicks  should  be  nicely 
formed,  hardened  and  tempered  and  polished  all  over  with 
emery.  Long,  thin  springs  will  be  needed  to  keep  the  wind- 
ing clicks  up  to  the  ratchet  teeth.  The  ratchet  wheel  must 
run  freely  on  the  barrel  arbor,  being  carried  round  by  the 
clicks  while  the  clock  is  going,  and  standing  still  while  the 
weight  is  being  wound  up.  It  is  retained  at  this  time  by  a 
long  detent  click  mounted  on  an  arbor  having  its  pivots 
fitted  to  holes  in  the  clock  frame.  The  same  remark  as  to 
planting  applies  to  this  click  as  well  as  the  others,  and  to  all 


THE    MODERN    CLOCK. 


289 


clicks  having  similar  objects;  but  as  this  chck  has  its  own 
weight  to  cause  it  to  fall  no  spring  is  required.  To  pre- 
vent it  lying  heavily  on  the  wheel,  causing  wear,  friction 
and  a  diminution  of  driving  power,  it  is  as  well  to  have  it 
made  light.  There  is  no  absolute  utility  in  fixing  the  click 
to  its  collet  with  screws,  but  if  done,  it  can  be  taken  off 
to  be  polished,  and  the  appearance  will  be  more  workman- 
like. This  click  should  have  its  point  hardened  and  tem- 
pered, as  there  is  considerable  wear  on  it. 

If  the  great  wheel  has  spokes  the  best  form  for  the  two 
springs  for  keeping  the  train  going  whilst  being  wound 
is  that  of  the  letter  U,  as  shown  to  the  left  of  Fig.  84,  one 
end  enlarged  for  the  screw  and  steady  pin  and  the  blade 
tapering  all  along  towards  the  end  which  is  free.  The 
springs  may  be  made  straight  and  bent  to  the  form  while 

n 


Fig.  87 

soft,  then  hardened  and  tempered  to  a  full  blue.  They  are 
best  when  as  large  as  the  space  between  two  arms  of  the 
main  wheel  will  allow.  When  screwed  on  the  large  ratchet 
the  backs  of  both  should  bear  exactly  against  the  respective 
arms  of  the  mainwheel,  and  a  pair  of  pins  is  put  in  the 
ratchet,  so  that  any  opposite  pair  of  the  mainwheel  arms 
may  rest  upon  them  when  the  springs  are  set  up  by  the 
clock  weight.  The  strength  of  the  springs  can  be  ad- 
justed by  trial,  reducing  them  till  the  weight  of  the  clock 
sets  them  up  easily  to  the  banking  pins. 

There  are  two  methods  of  keeping  the  loose  wheels 
against  the  end  of  the  barrel,  while  allowing  them  to  turn 
freely  during  winding ;  one  is  a  sliding  plate  with  a  keyhole 
slot,  Fig.  87,  to  slip  in  a  groove  on  the  arbor,  as  is  generally 
adopted  in  such  house  clocks  as  have  fuzees,  as  well  as  on 


290  THE    MODERN    CLOCK. 

the  barrels  of  old-fashioned  weight  clocks;  the  other  is  a 
collet  exactly  the  same  as  on  watch  fuzees.  They  are  both 
sufficiently  effective,  but  perhaps  the  latter  is  the  best  of  the 
two,  because  the  collet  may  be  fitted  on  the  arbor  with  a 
pipe,  and  being  turned  true  on  the  broad  inside  face,  gives 
a  larger  and  steadier  surface  for  the  mainwheel  to  work 
against,  whereas  the  former  only  has  a  small  bearing  on  the 
shoulder  of  the  small  groove  in  the  arbor,  which  fitting  is 
Hable  to  wear  and  allow  the  main  and  the  other  loose  wheel 
to  wobble  sideways,  displacing  the  contact  with  the  detent 
click  and  causing  the  mainwheel  to  touch  the  collet  of  the 
center  wheel  if  very  near  together ;  so,  on  the  whole,  a  col- 
let, as  on  a  watch  fuzee,  seems  the  better  arrangement, 
where  there  is  plenty  of  room  for  it  on  the  arbor. 

There  is  an  older  form  of  maintaining  power  which  is 
sometimes  met  with  in  tower  clocks  and  which  is  sometimes 
imitated  on  a  small  scale  by  jewelers  who  are  using  a  cheap 
regulator  and  wish  to  add  a  maintaining  power  where  there 
is  no  room  between  the  barrel  and  plates  for  the  ratchets 
and  great  wheel. 

The  maintaining  power.  Fig.  88,  consists  of  a  shaft.  A,  a 
straight  lever,  B,  a  segment  of  a  pinion,  C,  a  curved,  double 
lever,  D,  a  weight,  E.  The  shaft,  A,  slides  endwise  to  en- 
gage the  teeth  of  the  pinion  segment  with  the  teeth  of  the 
great  wheel.  No.  2,  the  straight  lever  has  a  handle  at  both 
ends  to  assist  in  throwing  the  pinion  out  or  in  and  a  shield 
at  the  outer  end  to  cover  the  end  of  the  winding  shaft.  No. 
3,  when  the  key  is  not  on  it. 

The  curved  lever  is  double,  and  the  pinion  segment  turns 
loosely  between  the  halves  and  on  the  shaft,  A ;  it  is  held 
up  in  its  place  by  a  light  spring,  F;  the  weight,  E,  is  also 
held  between  the  two  halves  of  the  double  lever. 

The  action  is  as  follows :  The  end  of  the  lever,  B,  covers 
the  end  of  the  winding  shaft  so  that  it  is  necessary  to  raise 
it  before  putting  the  key  on  the  winding  shaft;  it  is  raised 
till  it  strikes  a  stop,  and  then  pushed  in  till  the  pinion  seg- 


THE    MODERN    CLOCK, 


291 


Fig.  88.    Maintaining  Power. 


292  THE    MODERN    CLOCK. 

ment  engages  with  the  going  wheel  of  the  train,  when  the 
weight,  E,  acting  through  the  levers,  furnishes  power  to 
drive  the  clock-train  while  the  going  weight  is  being  wound 
up.  Of  course  the  weight  on  the  maintaining  power  must 
be  so  proportioned  to  the  leverage  that  it  will  be  equal  to 
the  power  of  the  going  barrel  and  its  weight,  a  simple  prop- 
osition in  mechanics. 

The  number  of  teeth  on  the  pinion  segment,  C,  is  suffi- 
cient to  maintain  power  for  fifteen  minutes,  at  the  end  of 
which  time  the  lever,  B,  will  come  down  and  again  cover 
the  end  of  the  winding  shaft ;  or,  it  may  be  pumped  out  of 
gear  and  dropped  down.  In  case  it  is  forgotten,  the  spring, 
F,  will  allow  the  segment  to  pass  out  of  gear  of  itself  and 
will  simply  allow  it  to  give  a  click  as  it  slips  over  each 
tooth  in  the  going  wheel ;  if  this  were  not  provided  for,  it 
would  stop  the  clock. 


CHAPTER  XVI. 

MOTION   WORK   AND   STRIKING  TRAINS. 

Motion  work  is  the  name  given  to  the  wheels  and  pinions 
used  to  make  the  hour  hand  go  once  around  the  dial  while 
the  minute  hand  goes  twelve  times.  Here  a  few  prelimi- 
nary observations  will  do  much  toward  clearing  up  the 
operations  of  the  trains.  The  reader  will  recollect  that  we 
started  at  a  fixed  point  in  the  time  train,  the  center  arbor 
which  must  revolve  once  per  hour,  and  increased  this  mo- 
tion by  making  the  larger  wheels  drive  the  smaller  (pin- 
ions) until  we  reached  sixty  or  more  revolutions  of  the 
escape  wheel  to  one  of  the  center  arbor.  This  gearing  to 
increase  speed  is  called  "gearing  up"  and  in  it  the  pinions 
are  always  driven  by  the  wheels.  In  the  case  of  the  hour 
hand  we  have  to  obtain  a  slowing  effect  and  we  do  so  by 
making  the  smaller  wheels  (pinions)  drive  the  larger  ones. 
This  is  called  "gearing  back"  and  it  is  the  only  place  in 
the  clock  where  this  method  of  gearing  occurs. 

We  drew  attention  to  a  common  usage  in  the  gearing  up 
of  the  time  trains — ^that  of  making  the  relations  of  the 
wheels  and  pinions  8  to  one  and  7.5  to  one ;  7.5  X  8  =  60. 
So  we  find  a  like  usage  in  our  motion  work,  viz.,  3  to  one 
and  4  to  one ;  3X4=12.  Say  the  cannon  pinion  has 
twelve  teeth;  then  the  minute  wheel  generally  has  36,  or 
three  to  one,  and  if  the  minute  wheel  pinion  has  10,  the 
hour  wheel  will  have  40,  or  four  to  one.  Of  course,  any 
numbers  of  wheels  and  pinions  may  be  used  to  obtain  the 
same  result,  so  long  as  the  teeth  of  the  wheels  multiplied 
together  give  a  product  which  is  twelve  times  that  of  the 
pinions  multiplied  together ;  but  three  and  four  to  one  have 

293 


294  "^^^    MODERN    CLOCK. 

been  settled  upon,  just  as  the  usage  in  the  train  became 
fixed,  and  for  the  same  reasons;  that  is,  these  proportions 
take  up  the  least  room  and  may  be  made  with  the  least 
material.  Also,  the  pinion  with  the  greatest  number  of 
teeth,  being  the  larger,  is  usually  selected  as  the  cannon 
pinion,  as  it  gives  more  room  to  be  bored  out  to  receive  the 
cannon,  oi*  pipe.  If  placed  outside  the  clock  plate,  the  min- 
ute wheel  and  pinion  revolve  on  a  stud  in  the  clock  plate: 
but  if  placed  between  the  frames,  they  are  mounted  on 
arbors  like  the  other  w^heels.  The  method  of  mounting  is 
merely  a  matter  of  convenience  in  the  arrangement  of  the 
train  and  is  varied  according  to  the  amount  of  room  in  the 
movement,  or  convenience  in  assembling  the  movement  at 
the  factory,  little  attention  being  paid  to  other  considera- 
tions. 


o 


fc 


Fig.  89.  Fig.  90. 

The  cannon  pinion  is  loose  on  the  center  arbor  and  be- 
hind it  is  a  spring,  called  the  center  spring,  or  ''friction," 
Figs.  89  and  90,  which  is  a  disc  that  is  squared  on  the  arbor 
at  its  center  and  presses  at  three  points  on  its  outer  edge 
against  the  side  of  the  cannon  pinion;  or  it  may  be  two  or 
three  coils  of  brass  wire.  This  center  spring  thus  produces 
friction  enough  on  the  cannon  to  drive  it  and  the  hour 
hand,  while  permitting  the  hands  to  be  turned  backward  or 
forward  without  interfering  with  the  train.  In  French  man- 
tel clocks  the  center  spring  is  dispensed  with  and  a  portion 
of  the  pipe  is  thinned  and  pressed  in  so  as  to  produce  k 


THE    MODERN    CLOCK. 


295 


friction  between  the  pipe  and  the  center  arbor  which  is 
sufficient  to  drive  the  hands ;  this  is  similar  to  the  friction 
of  the  cannon  pinion  in  a  watch. 

In  some  old  English  house  clocks  w^ith  snail  strike,  the 
cannon  pinion  and  minute  wheel  have  the  same  number  of 
teeth  for  convenience  in  letting  off  the  striking  work  by 
means  of  the  minute  wheel,  which  thus  turns  once  in  an 
hour.    Where  this  is  the  case  the  hour  wheel  and  its  pinion 


^^\ 
7/N^- 


I 


Fig.  91. 


bear  a  proportion  to  each  other  of  twelve  to  one;  usually 
there  is  a  pinion  of  six  leaves  engaging  a  wheel  of  ^2  teeth, 
or  seven  and  eighty-four  are  sometimes  found. 

In  tower  clocks,  where  the  striking  is  not  discharged  by 
the  motion  w'ork,  the  cannon  pinion  is  tight  on  its  arbor 
and  the  motion  work  is  similar  to  that  of  watches.  See 
Fig.  91. 

The  cannon  pinion  drives  the  minute  wheel,  which,  to- 
gether with  its   pinion,  revolves  loosely  on  a  stud  in  the 


296  THE    MODERN    CLOCK. 

clock  plate,  or  on  an  arbor  between  the  frames.  The  mesh- 
ing of  the  minute  wheel  and  cannon  pinion  should  be  as 
deep  as  is  consistent  with  perfect  freedom,  as  should  also 
that  of  the  hour  wheel  and  minute  pinion  in  order  to  prevent 
the  hour  hand  from  having  too  much  shake,  as  the  minute 
wheel  and  pinion  are  loose  on  the  stud  and  the  hour  wheel 
is  loose  on  the  cannon,  so  that  a  shallow  depthing  here  will 
give  considerable  back  lash,  which  is  especially  noticeable 
when  winding. 

The  hour  wheel  has  a  short  pipe  and  runs  loosely  on  the 
cannon  pinion  in  ordinary  clocks.  In  quarter  strike  cuckoos 
a  different  train  is  employed  and  the  wheels  for  the  hands 
are  both  on  a  long  stud  in  the  plate  and  both  have  pipes; 
the  minute  wheel  has  32  teeth  and  carries  four  pins  on  its 
under  side  to  let  off  the  quarters.  The  hour  wheel  has  64 
teeth  and  works  close  to  the  minute  wheel,  its  pipe  sur- 
rounding the  minute  wheel  pipe,  and  held  in  position  by  a 
screw  and  nut  on  the  minute  pipe.  A  wheel  of  48  and  a 
pinion  of  8  teeth  are  mounted  on  the  sprocket  arbor  with  a 
center  spring  for  a  friction,  the  wheel  of  48  meshing  with 
the  minute  wheel  of  32  and  the  8-leaf  pinion  with  the  hour 
wheel  of  64.  It  will  be  recollected  that  the  sprocket  wheel 
takes  the  place  of  the  barrel  in  this  clock  and  there  is  no 
center  arbor  as  it  is  commonly  understood.  The  sprocket 
arbor  in  this  case  turns  once  in  an  hour  and  a  half,  hence  it 
requires  48  teeth  to  drive  the  minute  wheel  of  ^^  once  in 
an  hour,  as  it  turns  one-third  of  a  revolution  (or  16  teeth) 
every  half  hour.  The  sprocket  arbor,  turning  once  in  an 
hour  and  a  half,  makes  eight  revolutions  in  twelve  hours  and 
its  pinion  of  eight  leaves  working  in  the  hour  wheel  of  64 
teeth  turns  the  hour  hand  once  in  twelve  hours. 

In  ordinary  rack  and  snail  striking  work  the  snail  is  gen- 
erally mounted  on  the  pipe  of  the  hour  wheel,  so  that  it  will 
always  agree  with  the  position  of  the  hour  hand  and  the 
striking  will  thus  be  in  harmony  with  the  position  of  the 
hands. 


THE    MODERN    CLOCK.  297 

Striking  Trains. — It  is  only  natural,  after  finding  cer- 
tain fixed  relations  in  the  calculations  of  time  trains  and 
motion  work,  that  we  should  look  for  a  similar  point  in 
striking  trains,  well  assured  that  we  shall  find  it  here  also. 
It  is  evident  that  the  clock  must  strike  the  sum  of  the  num- 
bers 1,  2,  3,  4,  5,  6,  7,  8,  9,  10,  II,  12,  or  78  blows  of  the 
hammer,  in  striking  from  noon  to  midnight;  this  will  be 
repeated  from  midnight  to  noon,  making  156  blows  in  24 
hours,  and  if  it  is  a  30-hour  clock,  six  hours  more  must  be 
added;  blows  for  these  will  be  21  more,  making  a  total  of 
177  blows  of  the  hammier  for  a  30-hour  strike  train.  The 
hammer  is  raised  by  pins  set  in  the  edge  of  a  wheel,  called 
the  pin  wheel,  and  as  one  pin  must  pass  the  hammer  tail 
for  every  blow,  it  is  evident  that  the  number  of  pins  in  this 
wheel  will  govern  the  number  of  revolutions  it  must,  make 
for  177  blows,  so  that  here  is  the  base  or  starting  point  in 
our  striking  train.  If  there  are  13  pins  in  the  pin  wheel, 
it  must  revolve  13.5  times  for  177  blows ;  if  there  are  8  pins, 
then  the  wheel  must  revolve  22.125  times  in  giving  177 
blows;  consequently  the  pinions  and  wheels  back  to  the 
spring  or  barrel  must  be  arranged  to  give  the  proper  num- 
ber of  revolutions  of  the  pin  wheel  with  a  reasonable  num- 
ber of  turns  of  the  spring  or  weight  cord,  and  it  is  gen- 
erally desirable  to  give  the  same,  or  nearly  the  same,  num- 
ber of  turns  to  both  time  and  striking  barrels. 

If  it  is  an  eight-day  clock  the  calculation  is  a  little  differ- 
ent. There  are  156  blows  every  24  hours;  then  as  the  ma- 
jority of  "eight-day"  clocks  are  realiy  calculated  to  keep 
time  for  seven  and  a  half  days,  although  they  will  run 
eight,  we  have :  156  X  7-5  =  1,070  blows  in  7.5  days.  With 
13  pins  we  have  1,070 -f- 13  =  80  and  4-i3ths  revolutions 
in  the  7.5  days.  If  now  we  put  an  8-leaf  pinion  on  the  pin 
wheel  arbor  and  84  teeth  in  the  great  wheel  or  barrel,  we 
will  get  10.5  turns  of  the  pin  wheel  for  every  turn  of  the 
spring  or  barrel ;  consequently  eight  turns  of  the  spring  will 


298  THE    MODERN    CLOCK. 

be  enough  to  run  the  clock  for  the  required  time,  as  such 
clocks  are  wound  every  seventh  day. 

Figuring  forward  from  the  pin  wheel,  we  find  that  we 
shall  have  to  lock  our  striking  train  after  a  stated  number 
of  blows  of  the  hammer -each  hour;  these  periods  increase 
by  regular  steps  of  one  blow  every  hour,  so  that  we  must 
have  our  locking  mechanism  in  position  to  act  after  the 
passage  of  each  pin,  whether  it  is  then  used  or  not ;  so  the 
pinion  that  meshes  with  the  pin  wheel,  and  carries  the  lock- 
ing plate  or  pin  on  its  arbor  must  make  one  revolution  every 
time  it  passes  a  pin.  If  this  is  a  6-leaf  pinion,  the  pins  on 
the  pin  wheel  must  therefore  be  6  teeth  apart;  or  an  8-leaf 
pinion  must  have  the  pins  8  teeth  apart;  and  vice  versa. 
For  greater  convenience  in  registering,  the  pins  are  set  in 
a  radial  line  with  the  spaces  of  the  teeth  in  the  pin  wheel, 
as  this  allows  us  to  measure  from  the  center  of  the  pinion 
leaf. 

It  will  thus  be  seen  that  the  calculation  of  an  hour  striking 
train  is  a  simple  matter;  but  if  half  hours  are  also  to  be 
struck  from  the  train,  it  will  change  these  calculations. 
For  a  30-hour  train  24  must  be  added  to  the  156  blows  for 
24  hours,  180  blows  being  required  to  strike  hours  and  half 
hours  for  24  hours.  These  blows  may  be  provided  for  by 
more  turns  of  the  spring,  or  different  numbers  of  the  wheels 
and  pinions,  which  would  then  also  vary  the  spacing  of  the 
pins. 

Half  hours  may  also  be  struck  directly  from  the  center 
arbor,  by  putting  an  extra  hammer  tail  on  the  hammer 
arbor,  further  back,  where  it  will  not  interfere  with  the 
hammer  tail  for  the  pin  wheel,  and  putting  a  cam  on  the 
center  arbor  to  operate  this  second  hammer  tail.  This 
simplifies  the  train,  as  it  enables  the  use  of  a  shorter  spring 
or  smaller  wheels  while  providing  a  cheap  and  certain 
means  of  striking  the  half  hours.  Half-hour  trains  are 
frequently  provided  with  a  separate  bell  of  different  tone  for 
the  half  hours,  as  with  only  one  bell  the  clock  strikes  one 


THE    MODERN    CLOCK. 


299 


Fig.  92.    Eight  Day  Hour  and  Half  Hour  Strike. 


300  THE    MODERN    CLOCK. 

blow  at  12  .-30,  I  and  1 130,  making  the  time  a  matter  of 
doubt  to  one  who  Hstens  without  looking,  as  frequently 
happens  in  the  night. 

Fig.  92  shows  an  eight-day,  Seth  Thomas  movement, 
which  strikes  the  hours  on  a  count  wheel  train  and  the  half 
hours  from  the  center  arbor.  All  the  wheels,  pinions,  ar- 
bors, pins,  levers  and  hooks  are  correctly  shown  in  proper 
position,  but  the  front  plate  has  been  left  off  for  greater 
clearness.  The  reader  will  therefore  be  required  to  remem- 
ber that  the  escape  wheel,  pallets,  crutch,  pendulum  and  the 
stud  for  the  pendulum  suspension  are  really  fixed  to  the 
front  plate,  while  in  the  drawing  they  have  no  visible 
means  of  support,  because  the  plate  is  left  off. 

The  time  train  occupies  the  right-hand  side  of  the  move- 
ment and  the  striking  train  the  left-hand.  Running  up  the 
right  hand  from  the  spring  to  the  escape  wheel,  we  find  an 
extra  wheel  and  pinion  which  is  provided  to  secure  the 
eight  days'  run.  We  also  see  that  what  would  ordinarily 
be  the  center  arbor  is  up  in  the  right  corner  and  does  not 
carry  the  hands;  further,  the  train  is  bent  over  at  a  right 
angle,  in  order  to  save  space  and  get  the  escape  wheel  in 
the  center  at  the  top  of  the  movement.  The  striking  train 
is  also  crowded  down  out  of  a  straight  line,  the  locking 
cam  being  to  the  right  of  the  pin  wheel  and  the  warning 
wheel  and  fly  as  close  to  the  center  as  possible.  This  leaves 
some  space  between  the  pin  wheel  and  the  intermediate 
wheel  of  the  time  train  and  here  we  find  our  center  arbor, 
driven  from  the  intermediate  wheel  by  an  extra  pinion  on 
the  minute  wheel  arbor,  the  minute  wheel  meshing  with 
the  cannon  pinion  on  the  center  arbor.  This  rearranging 
of  trains  to  save  space  is  frequently  done  and  often  shows 
considerable  ingenuity  and  skill ;  it  also  will  many  times 
serve  to  identify  the  maker  of  a  movement  when  its  origin 
is  a  matter  of  doubt  and  we  need  some  material,  so  that 
the  planting  of  trains  is  not  only  a  matter  of  interest,  but 


THE    MODERN    CLOCK.  3OI 

should  be  studied,  as  familiarity  with  the  methods  of  vari- 
ous factories  is  frequently  of  service  to  the  watchmaker. 

Fig.  93  is  the  upper  portion  of  the  same  striking  train, 
drawn  to  a  larger  scale  for  the  sake  of  clearness.  It  also 
shows  the  center  arbor,  both  hammer  tails  and  the  stop  on 
the  hammer  arbor,  which  strikes  against  the  bottom  of  the 
front  plate  to  prevent  the  hammer  spring  from  throwing  the 
hammer  out  of  reach  of  the  pins.  The  pin  wheel,  R,  and 
count  wheel,  E,  are  mounted  close  together  and  are  about 
the  same  size,  so  that  they  are  shown  broken  away  for  a 
part  of  their  circumferences  for  greater  clearness  in  ex- 
plaining the  action  of  the  locking  hook,  'C,  and  the  locking 
cam,  D. 

Fig.  94  shows  the  same  -  parts  in  the  striking  position, 
being  shown  as  just  about  to  strike  the  last  blow  of  12. 
Similar  parts  have  similar  letters  in  both  figures. 

The  count  wheel,  E,  is  loose  on  a  stud  in  the  Dlatc,  con- 
centric with  the  arbor  of  the  pin  wheel,  R.  The  pivot  of  R 
runs  through  this  stud.  The  sole  office  of  the  count  wheel 
is  to  regulate  the  distance  to  which  the  locking  hook  C,  is 
allowed  to  fall.  The  count  hook,  A,  and  the  locking  hook, 
C,  are  mounted  on  the  same  arbor,  B,  so  that  they  move  in 
unison.  If  A  is  allowed  to  fall  into  a  deep  slot  of  the  count 
wheel,  C  will  fall  far  enough  to  engage  the  locking  face  of 
the  cam  D  and  stop  the  train,  as  in  Fig.  93.  If,  on  the 
contrary,  A  drops  on  the  rim  of  the  wheel,  C  will  be  held 
out  of  the  locking  position  as  D  comes  around  (see  Fig. 
94),  and  the  train  will  keep  on  running.  It  will  be  seen 
that  after  passing  the  locking  notch,  D,  Fig.  94,  will  in  its 
turn  raise  the  hook  C,  which  will  ride  on  the  edge  of  D, 
and  hold  A  clear  of  the  count  wheel  until  the  locking  notch 
of  D  is  again  reached,  when  a  deep  notch  in  the  wheel  will 
allow  C  to  catch,  as  in  Fig.  93,  unless  C  is  stopped  by  A 
falHng  on  the  rim  of  the  wheel,  as  in  Fig.  94. 

One  leaf,  F,  of  the  pinion  of  the  locking  arbor  sticks  out 
far  enough  to  engage  with  the  count  wheel  teeth  and  rotate 


302 


THE    MODERN    CLOCK. 


Fig.  93.     Upper  Portion  of  Striking  Train  Locked. 


THE    MODERN    CLOCK. 


303 


Fig.  94.    Striking  Train  Unlocked  and  Running. 


3^4 


illK    IvIODEIlN    CJ.OCK. 


the  wheel  one  tooth  for  each  revolution  of  D,  so  that  F 
forms  a  one-leaf  pmion  similar  to  that  of  a  rack  striking' 
train.  Here  we  have  our  counting  mechanism ;  F  and  D 
go  around  together ;  F  moves  E  one  tooth  every  revolution. 
A  holds  C  out  of  action  (Fig.  94)  until  A  reaches  a  deep 
slot,  when  C  stops  the  train  by  engaging  D  (Fig.  93). 

The  count  wheel,  E,  must  have  friction  enough  on  its 
stud  so  that  it  will  stay  where  the  pin  F  leaves  it,  -when  F 
goes  out  of  action  and  thus  it  will  be  in  the  right  "position  ta 
suitably  engage  F  on  the  next  revolution.  Too  much  fric- 
tion of  the  count  wheel  on  its  stud  will  use  too  much  power 
for  F  to  move  it  and  thus  slow  the  train;  if  there  is  too  little 
friction  here  the  count  wheel  may  get  in  such  a  position 
that  F  will  get  stalled  on  the  top  of  a  tooth  and  stop  the 
train. 

The  count  hook,  A,  must  strike  exactly  in  the  middle  of 
the  deep  slots,  without  touching  the  sides  of  the  slots  in 
entering  or  leaving,  as  to  do  this  would  shift  the  position  of 
the  count  wheel  if  the  rubbing  were  sufficient,  or  it  might 
prevent  A  from  falling  (as  A  and  C  are  both  very  light) 
and  the  clock  would  go  on  striking.  If  the  hook  A  does  not 
strike  the  middle  of  the  spaces  between  the  teeth  of  the 
count  wheel,  it  will  gradually  encroach  on  a  tooth  and  push 
the  wheel  forward  or  back,  thus  disarranging  the  count. 
Many  a  clock  has  struck  13  for  12  in  this  way  because  the 
hook  was  a  little  out.  This  did  not  occur  in  the  smaller 
numbers  because  the  action  w^as  not  continued  long  enough 
to  allow  the  hook  to  reach  a  tooth.  The  pin,  F,  should  also 
mesh  fairly  and  freely  in  the  teeth  of  the  count  wheel,  or 
a  similar  defect  is  likely  to  occur. 

When  repairing  or  making  new  count  hooks,  A,  Figs. 
93  and  94,  ihey  must  be  of  such  a  length  that  they  will  enter 
the  slots  on  a  line  radial  with  the  center  of  the  wheel.  The 
proper  length  and  direction  are  shown  at  A,  Fig.  95,  while 
B  and  C  are  wrong.  With  hooks  like  either  B  or  C  you 
can  set  or  bend  the  hook  to  strike  right  at  one  and  as  you 


IIE    MOl^EKN    CLOCK. 


305 


turn  the  clock  ahead  the  hook  does  not  fall  in  far  enough 
and  at  twelve  it  only  strikes  eleven.  Then  if  you  bend  the 
same  hook  to  strike  right  at  twelve  it  will  strike  two  at  one 
and  as  you  turn  the  clock  ahead  it  will  strike  right  at  about 
five  or  seven.  A, Fig.  95,  being  of  the  proper  length  and  shape 
will  give  no  trouble.  ■  Many  of-the  count  wheels  of  the  older 
clocks  w^ere  divided  by  hand  and  are  not  as  accurate  as 
they  should  be ;  when  a  wheel  of  this  kind  is  found  and  a 
new'-  w^heel  cannot  be  substituted   (because  the  clock  is  an 


Fig.  95,     The  proper  length  of  the  count  hook. 


antique  and  must  have  the  original  parts  preserved)  it  will 
sometimes  require  nice  management  of  the  hook  A  to  obtain 
correc  striking.  A  little  manipulation  of  the  pinion,  F, 
Fig  93  is  sometimes  desirable  also,  if  the  count  wheel  is 
very  bad. 

.  The  locking  face  of  the  cam,  D,  must  also  be  on  a  line 
radial  to  its  center,  or  it  will  either  unlock  too  easily  and 
go  off  on  the  slightest  jar  or  movement  of  the  clock,  or  the 
face  will  have  too  much  draw  and  the  hook  C  will  not  be 
unlocked  when  the  clock  is  fully  wound,  and  the  spring 
pressure  is  greatest.  In  this  case  the  clock  will  not  strike 
when  fully  wound,  but  will  do  so  when  partly  run  down, 


306  THE    MODERN    CLOCK. 

and  as  the  count  wheel  train  strikes  in  rotation,  without  re- 
gard to  the  position  of  the  hands,  you  will  have  irregular 
striking  of  a  most  puzzling  sort.  Repairs  to  this  notch  are 
sometimes  required,  when  the  corner  has  become  rounded, 
and  the  best  way  to  make  them  is  to  cut  a  new  face  on  the 
cam  with  a  sharp  graver,  being  careful  to  keep  the  face 
radial  with  its  center. 

Because  the  count  wheel  strikes  the  hours  in  rotation, 
regardless  of  the  position  of  the  hands,  if  the  hands  are 
turned  backwards  past  the  figure  12  on  the  dial  the  striking 
will  be  thrown  out  of  harmony  with  the  hands.  To  remedy 
this  the  count  hook.  A,  has  an  eye  on  its  rear  end  and  a 
wire,  shown  in  Fig.  92,  hangs  down  to  where  it  can  be 
reached  with  the  hand  when  the  dial  is  on.  Pulling  this 
wire  will  lift  A  and  C  and  cause  the  clock  to  strike ;  by  this 
means  the  clock  may  be  struck  around  until  the  position  of 
the  striking  train  agrees  with  that  of  the  hands.  Where 
this  wire  is  not  present  the  striking  is  corrected  by  turning 
the  hands  back  and  forth  between  IX  and  XII  until  the 
proper  hour  is  struck. 

Now  we  come  to  the  releasing  mechanism,  which  causes 
the  clock  to  strike  at  stated  times.  I,  Figs.  93  and  94,  is  an 
arbor  pivoted  between  the  plates  and  carrying  three  levers, 
H,  K  and  J,  in  different  positions  on  the  arbor.  H  is  directly 
under  the  count  hook,  A,  and  lifts  A  and  C  whenever  J  is 
pushed  far  enough  to  one  side  by  L  on  the  center  arbor, 
which  revolves  once  an  hour.  Thus  L,  through  J,  H  and 
A,  C,  unlocks  the  train  once  every  hour.  When  C  is  thus 
lifted  the  train  runs  until  the  warning  pin,  O,  Figs.  93  and 
94,  strikes  against  the  lever  K,  which  is  on  the  same  arbor 
with  H  and  J.  This  preliminary  run  of  the  train  makes  a 
little  noise  and  is  called  "warning,"  as  the  noise  notifies 
us  that  the  train  is  in  position  to  commence  striking.  The 
lever  K  and  the  warning  pin,  O,  then  hold  the  train  until 
L  has  been  carried  out  of  action  with  J  and  released  it,  when 


THE    MODERN    CLOCK.  307 

O  will  push  K  out  of  its  path  at  every  revolution  and  the 
clock  will  strike. 

The  half  hours  are  struck  by  L^  pressing  the  short  ham- 
mer tail,  G\  and  thus  raising  and  releasing  the  hammer  once 
an  hour. 

In  setting  up  the  striking  train  after  cleaning,  place  the 
pin  wheel  so  that  the  hammer  tail,  G,  may  be  about  one- 
fourth  of  the  distance  from  the  next  pin,  as  shown  in  Fig. 
93 ;  this  allows  the  train  to  get  well  under  way  before  meet- 
ing with  any  resistance  and  will  insure  its  striking  when 
nearly  run  down.  If  the  hammer  tail  is  too  close  to  the  pin, 
it  might  stop  the  train  when  there  is  but  little  power  on. 

Then  place  D  in  the  locked  position,  wath  A  in  a  deep 
slot  of  the  count  wheel  and  C  in  the  notch  of  D.  Next 
place  the  warning  wheel  with  its  pin,  O,  on  the  opposite  side 
of  its  arbor  from  the  lever  K,  see  Fig.  93.  This  is*  done  to 
make  sure  that  when  it  is  unlocked  for  "warning"  the  train 
will  run  far  enough  to  get  the  corner  of  the  lock,  D,  safely 
past  C,  so  that  it  will  not  allow  C  to  fall  into  the  notch  again 
and  lock  the  train  when  J,  K  and  H  are  released  by  L.  This 
is  the  rule  followed  in  assembling  these  clocks  at  the  fac- 
tories and  is  simple,  correct  and  easily  understood.  A  study 
of  these  points  in  Fig.  93. will  enable  any  one  to  set  up  a 
train  correctly  before  putting  the  front  plate  on. 

If  the  workman  gets  a  clock  that  has  been  butchered  by 
some  one  who  did  not  understand  it  (and  there  are  many 
such),  he  may  find  that  when  correctly  set  up  the  clock 
does  not  strike  on  the  60th  minute  of  the  hour ;  in  such  a 
case  a  little  bending  of  J,  in  or  out  as  the  case  may  be,  will 
usually  remedy  the  trouble.  The  same  thing  may  have  to 
be  done  to  the  hammer  tails,  G  and  G^,  or  the  stop  on  the 
hammer  arbor.  If  both  hammer  tails  are  out  of  position, 
bend  the  stop;  if  one  is  right,  let  the  stop  alone  and  bend 
the  other  tail. 

A  rough,  set  or  gummy  spring  will  cause  irregular  stri- 
king.   In  such  a  case  the  clock  will  strike  part  of  the  blows 


308  THE    MODERN    CLOCK. 

and  then  stop  and  finally  go  on  again  and  complete  the 
number.  Much  time  has  been  lost  in  examining  the  teeth 
of  wheels  and  pinions  in  such  cases  when  the  trouble  lay 
in  the  spring.  Too  strong  a  spring  will  make  the  move- 
ment strike  too  fast;  too  weak  a  spring  will  make  it  strike 
slow,  especially  in  the  latter  part  of  the  day  or  week,  when 
it  has  nearly  run  down. 

Too  small  a  fan,  or  a  fan  that  is  loose  on  its  arbor,  will 
allow  the  clock  to  strike  too  fast.  If  this  fan  is  badly  out 
of  balance  it  will  prevent  the  train  from  starting  when 
there  is  but  little  power  on. 

There  is  a  class  of  clocks  which  have  the  count  wheel 
tight  on  the  arbor,  outside  the  clock  plate.  Many  of  them 
are  on  much  tighter  than  they  should  be.  In  such  a  case 
take  an  alcohol  lamp  and  heat  the  wheel  evenly,  especially 
around  the  hub;  the  brass  will  expand  twice  as  much  as 
the  steel  and  the  wheel  may  then  be  driven  off  without 
injury. 

Fig.  96  shows  another  typical  American  eight-day  train, 
made  by  the  Gilbert  Clock  Company,  and  striking  the  half 
hours  from  the  train.  Here  we  notice,  on  comparing  with 
Fig.  92,  that  there  are  many  points  of  difference.  First 
the  notches  on  the  count  wheel,  are  twice  as  wide  as  they 
are  in  Fig.  92.  This  means  that  half  hours  are  struck  on 
the  train;  this  will  be  explained  later.  Next  there  are  two 
complete  sets  of  notches  on  the  wheel,  which  shows  that 
the  wheel  turns  only  once  in  twenty-four  hours,  whereas 
the  other  makes  two  revolutions  in  that  time.  There  are 
no  teeth  on  the  count  wheel,  so  that  it  must  be  fast  to  its 
arbor,  which  is  that  of  the  great  wheel  and  spring,  while 
Fig.  92  has  a  separate  stud  and  it  is  loose.  The  wheel  being 
on  the  spring  arbor  and  going  once  in  24  hours,  there  must 
be  one  turn  of  spring  for  each  24  hours  which  the  train 
runs.  There  is  no  pin  wheel  in  Fig.  96,  but  instead  of  this 
two  pins  are  cut  out  of  the  locking  cam  to  raise  the  hammer 
tail  as  they  pass.     There  are  also  two  locking  notches  in 


THE    MODERN    CLOCK. 


309 


Fig.  96.    Half  hours  struck  on  the  train. 


3IO  THE    MODERN    CLOCK. 

the  locking  cam.    The  cams  on  the  center  arbor  are  stamped 
out  of  brass  sheet,  while  those  of  Fig.  92  were  of  wire. 

Turning  to  the  enlarged  view  in  Fig.  97  and  comparing 
it' with  Fig.  93,  we  find  further  differences.  The  levers 
K  and  J  are  here  made  of  one  piece  of  brass,  while  the 
others  were  separate  and  of  wire.  The  lifting  lever,  H,  is 
flattened  at  its  outer  end  in  Fig.  93,  while  in  Fig.  97  it  is 
bent  at  right  angles  and  passed  under  the  count  hook,  A. 
The  hook,  C,  Fig.  97,  is  added  to  the  arbor,  B,  as  a  safety 
device,  in  case  the  locking  hook  should  fail  to  enter  its  slot 
in  the  cam,  D.  It  is  shown  as  having  just  stopped  the  warn- 
ing pin  in  Fig.  96.  There  is  but  one  hammer  tail,  G,  and 
the  hammer  stop  acts  against  the  stud  for  the  hammer 
spring,  instead  of  against  the  bottom  of  the  front  plate,  as 
in  Fig.  92. 

The  first  important  difference  here  is  in  the  position  of 
the  count  hook,  A.  In  Figs.  92  and  93  the  hook  must  be 
exactly  in  the  middle  of  the  slot,  or  there  will  be  trouble. 
In  trains  striking  half  hours  from  the  train,  we  must  never 
allow  the  hook  to  occupy  the  middle  of  the  slot,  or  we  will 
have  more  trouble  than  we  ever  dreamed  of.  In  this  in- 
stance the  count  hook  must  enter  the  slot  close  to  (but  not 
touching)  the  side  of  the  slot  when  the  clock  stops  striking; 
then  when  the  half  hour  is  struck  the  count  wheel  will 
move  a  little  and  the  hook  must  drop  back  into  the  same 
slot  without  touching;  this  brings  it  close  to  the  opposite 
side  of  the  same  slot  and  the  next  movement  will  land  the 
hook  safely  on  top  of  the  wheel  for  the  strokes  of  the  hour. 
Fig.  96  shows  its  position  after  striking  the  half  hour  and 
ready  to  strike  the  hour  of  two.  Fig.  97  shows  it  dropping 
back  after  striking  two. 

In  setting  up  this  train,  see  that  the  count  hook,  A,  goes 
into  the  slot  of  the  count  wheel  close  to,  but  not  touching, 
one  side  of  the  slot  in  the  count  wheel,  and,  after  placing 
the  intermediate,  insert  the  locking  cam,  D,  so  that  it  en- 
gages the  locking  hook;    then  put  in  the  warning  wheel 


THE    MODERN    CLOCK. 


31^ 


Fig.  97 .    Half  hour  strike  on  the  count  wheel. 


312  THE  :modern  clock. 

with  the  warning  pin,  O,  safely  to  the  left  of  the  hook  C, 
Fig.  97,  so  that  it  cannot  get  past  that  hook  after  striking. 
Placing  the  wheel  with  its  warning  pin  six  or  eight  teeth 
to'  the  left  of  the  edge  of  the  bottom  plate  is  generally  about 
right.  The  action  of  the  levers,  H,  J,  K,  the  hammer  tail, 
G,  and  the  cam,  L,  in  striking  the  hours  is  the  same  as  that 
already  described  in  detail  for  Figs.  93  and  94,  hence  need 
not  be  repeated  here.  L^  strikes  the  half  hours  by  being 
enough  shorter  than  L  to  raise  the  hooks  for  one  revolution, 
but  not  quite  so  high  as  for  the  hours.  The  cams  L,  L^  are 
friction  tight  on  the  center  arbor  and  may  be  shifted  on  the 
arbor  to  register  the  striking  on  the  60th  minute,  if  desired. 
When  the  hands  and  strike  do  not  agree,  turn  the  minute 
hand  back  and  forward  between  IX  and  XII,  thus  striking 
the  clock  around  until  it  agrees  with  the  hands. 

Sometimes,  if  the  warning  pin  is  not  far  enough  away, 
an  eight-day  clock  will  strike  all  right  for  a  number  of  days 
and  then  commence  to  gain  or  lose  on  the  striking  side.  It 
either  does  not  strike  at  some  hours,  or  half  hours,  or  it 
may  strike  sometimes  both  hour  and  half  hour  before  stop- 
ping. Take  the  movement  out  of  the  case  and  put  the  hands 
on;  then  move  the  minute  hand  around  slowly  until  the 
clock  warns.  Look  carefully  and  be  sure  there  is  no  dan- 
ger of  the  clock  striking  when  it  warns.  If  this  looks  secure, 
then  move  the  hand  to  the  hour,  making  it  strike;  say  it  is 
going  to  strike  9  o'clock;  when  it  has  struck  eight  times, 
stop  the  train  with  your  finger  and  let  the  wheels  run  very 
slow  while  striking  the  last  one,  and  when  the  rod  drops 
into  the  last  notch  stop  the  train  again  and  hold  it  there. 

For  the  striking  part  to  be  correct,  the  warning  pin  on 
the  wheel  wants  to  be  about  one-fourth  of  a  revolution 
away  from  the  rod  when  the  clock  has  struck  the  last  timxC, 
or  as  soon  as  this  rod  falls  down  far  enough  to  catch  the 
pin.  The  object  of  this  is  so  there  is  no  chance  of  the 
warning  pin  getting  past  the  rod  at  the  last  stroke;  this  it 
is  liable  to  do  if  the  pin  is  too  close  to  the  rod  when  the 


THE    MODERN    CLOCK.  313 

rod  drops.  If  you  will  examine  the  clock  as  above,  not  only 
when  it  strikes  IX,  but  all  the  hours  from  I  to  XII,  you  will 
generally  find  the  fault.  Of  course,  if  the  pin  is  too  close 
to  the  rod  when  the  rod  drops,  you  must  lift  the  plates  apart 
and  change  the  wheel  so  that  the  warning  pin  and  the  rod 
will  be  as  explained. 

Ship's  Bell  Striking  Work. — Of  all  the  count  wheel 
striking  work  which  comes  to  the  watchmaker,  the  ship's 
bell  is  most  apt  to  give  him  trouble.  This  generally  arises 
from  ignorance  as  to  what  the  system  of  bells  on  shipboard 
consists  of  and  how  they  should  be  struck.  If  he  goes  to 
some  nautical  friend,  he  hears  of  long  and  short  ''watches" 
or  "full  watches"  and  "dog  watches."  If  he  insists  on  de- 
tails, he  gets  the  information  that  a  "watch"  is  not  a  horo- 
logical  mechanism,  but  a  period  of  duty  for  a  part  of  the 
crew.  Then  he  is  told  of  the  "morning  watch,"  "first  dog 
w^atch,"  "afternoon  watch,"  "second  dog  watch,"  "off 
watch,"  "on  watch,"  etc.  Now  the  ship's  bell  clock  does 
not  agree  with  these  "watches"  and  was  never  intended  to 
do  so.  As  a  matter  of  fact,  it  is  simply  a  clock  striking 
half  hours  from  one  to  eight  and  then  repeating  through 
the  twenty-four  hours. 

The  striking  is  peculiarly  timed  and  is  an  imitation  of 
the  method  in  which  the  hours  are  struck  on  the  bell  of 
the  ship.  As  this  bell  is  also  used  for  other  purposes,  such 
as  tolling  in  fogs,  fire  alarms,  church  services,  etc.,  it  will 
readily  be  seen  that  a  different  method  of  striking  for  each 
purpose  is  desirable  to  avoid  misunderstanding  of  signals. 

The  method  of  striking  for  time  is  to  give  the  blows  in 
couples,  with  a  short  interval  between  the  strokes  of  the 
couples  and  three  times  that  interval  between  the  couples. 
Odd  strokes  are  treated  as  a  portion  of  the  next  couple  and 
separated  accordingly,  thus: 


314  THE    MODERN    CLOCK. 


Fig.  98.    Ships  bell  clock. 


THE    MODERN    CLOCK.  315 

12:30  p.  m.  One  Bell,  O 

I  :oo  p.  m.  Two  Bells,  O  O 

I  :30  p.  m.  Three  Bells,  O  O 

2:00  p.  m.  Four  Bells,  O  O 

2:30  p.  m.  Five  Bells,  O  O 

3  :oo  p.  m.  Six  Bells,  O  O 

3  :30  p.  m.  Seven  Bells,  O  O 

4:00  p.  m.  Eight  Bells,  O  O 

After  striking  eight  bells  the  clock  repeats,  although  the 
ship's  bell  is  generally  struck  in  accordance  with  the  two 
dog  watches  (which  are  of  two  hours'  duration  each)  be- 
fore commencing  the  evening  watch  (8  to  12  p.  m.).  It 
will  thus  be  seen  that  the  clock  should  strike  eight  at  12  m., 
4  p.  m.,  8  p.  m.,  12  p.  m.,  4  a.  m,,  and  8  a.  m. 

In  order  to  strike  the  blows  in  pairs  two  hammers  are 
necessary,  see  Fig.  98;  these  hammers  are  placed  close  to- 
gether, but  not  in  the  same  plane.  The  pin  wheel  has  twenty 


0 

0     0 

0     0 

0 

0     0 

0     0 

0     0 

0     0 

0 

0     0 

0     0 

0     0 

t,  ,T   T    I  1,   I    T   »',T   I   1,  I    f'.T   T,  i;T-I   T   T 


I'       r'    'I    ■  I      •     'I  LxJ     "LlJI 


Fig.  100.    The  pins  on  the  count  wheel  of  the  ships  bell  clock. 

pins,  see  Figs.  98,  99,  100;  some  of  these  pins  are  shorter 
than  the  others,  so  that  they  do  not  operate  one  of  the  ham- 
mer tails.  These  are  shown  graphically  in  Fig.  100 ;  where 
the  two  oblong  marks  at  figure  i  represent  the  tops  of  the 
hammer  tails  shown  in  Fig.  99.  It  will  be  seen  by  studying 
Fig.  100  that  with  the  wheel  moving  from  left  to  right,  the 
inside  hammer  tail  will  be  operated  for  one  blow,  while  the 


3i6 


THE    MODERN    CI.OCK, 


Fig.  99.    Enlarged  view  of  striking  work,  ships  bell  clock. 


TlIK    MODERN    CLOCK.  317 

outer  hammer  tail  will  not  De  operated  at  all,  thus  giving 
but  one  blow,  or  "bell."  At  the  next  movement  of  the  pin 
wheel,  the  outside  hammer  will  be  operated  by  the  long  pin 
and  the  inside  hammer  by  the  short  pin,  thus  giving  one 
blow  of  each  hammer,  or  "two  bells." 

We  now  have  these  hammer  tails  advanced  along  the 
wheel  so  that  the  outside  one  is  opposite  the  figure  3  in  the 
drawing,  while  the  other  is  opposite  the  figure  2,  with  one 
pin  between  them.  The  next  movement  of  the  pin  wheel 
advances  them  so  that  the  outside  hammer  will  pass  the 
next  short  pin  and  consequently  that  hammer  will  miss  one 
blow  and  the  pair  will  therefore  strike  three — one  by  the 
outside  hammer  and  two  by  the  inside.  It  thus  goes  on 
until  the  cycle  is  completed,  eight  blows  being  struck  with 
the  last  four  pins.  The  striking  in  pairs  is  effected  by 
having  the  two  hammer  tails  close  together,  so  that  the 
pins  will  operate  both  hammer  tails  quickly  and  there  will 
then  be  an  interval  of  time  while  the  wheel  brings  forward 
the  next  pins.  This  is  so  spaced  that  the  interval  between 
pairs  is  three  times  that  between  the  blows  of  a  pair  and 
the  hammer  tails  should  not  be  bent  out  of  this  position,  or 
if  found  so  they  should  immediately  be  restored  to  it.  Toll- 
ing the  bells,  instead  of  striking  them  properly,  is  very  bad 
form  at  sea  and  generally  leads  to  punishment  if  persisted 
in,  so  that  the  jeweler  will  readily  perceive  that  his  marine 
customers  are  very  particular  on  this  point,  and  he  should 
go  any  length  to  obtain  the  proper  intervals  in  striking. 

The  pin  wheel  moves  forward  one  pin  for  each  couple 
of  blows  or  parts  of  a  couple,  the  odd  blows  being  secured 
by  the  failure  of  the  blow  w^hen  the  hammer  tail  passes  the 
short  pin.  Thus  it  moves  as  far  for  one  bell  as  for  two 
bells;  as  far  for  three  bells  as  for  four,  etc.  The  result  is 
that  the  count  wheel  has  no  odd  numbers  on  it,  but  instead 
two  2's,  two  4's,  two  6's  and  tw^o  8's ;  the  first  two  are 
counted  on  the  count  wheel,  but  only  one  is  struck  on  the 
pin  wheel,  owing  to  the  short  pin ;  this  is  repeated  at  three, 


3l8  THE    MODERN    CLOCK. 

five  and  seven,  when  four,  six  and  eight  are  counted  on 
the  wheel,  but  the  last  blow  fails  of  delivery,  owing  to  the 
short  pin  in  the  pin  wheel  at  these  positions. 

The  center  arbor  carries  two  pins,  L  and  L^,  to  unlock 
the  train  through  the  lever  J,  as  it  is  really  a  half-hour- 
striking  clock.  The  count  hook,  A ;  locking  hook,  C ;  count 
wheel,  E;  pins,  P,  and  other  parts  have  similar  letters  for 
similar  parts  as  in  the  preceding  figures  and  need  not  be 
further  explained,  as  the  mechanism  is  otherwise  similar 
to  the  Seth  Thomas  movement  shown  in  Fig.  92. 


CHAPTER  XVIL 

CLEANING  AND  REPAIRING  CUCKOO  CLOCKS. 

The  cuckoos  are  in  a  class  by  themselves  for  several  rea- 
sons, all  of  which  have  to  do  with  their  construction  and 
should  therefore  be  understood  by  the  watchmaker.  They 
are  bought  as  timepieces  by  but  two  classes  of  people :  those 
who  were  used  to  them  in  their  former  homes  in  Europe 
and  buy  them  for  sentimental  reasons;  and  those  who  ad- 
mire fine  wood  carvings  as  works  of  art  and  desire  to  pos- 
sess a  finely  carved  cuckoo  clock  for  the  reasons  which 
govern  in  the  purchase  of  paintings  and  statuary,  bronzes, 
and  other  art  objects.  For  this  reason  cuckoos  have  never 
been  a  success  when  attempts  have  been  made  to  cheapen 
their  production  by  the  use  of  imitations  of  wood  carving  in 
composition  or  metal.  The  use  of  cuckoos  in  plain  cases, 
with  springs  instead  of  weights,  has  also  been  attempted 
with  the  idea  of  thereby  securing  an  inclosed  movement, 
as  in  ordinary  clocks;  but  while  it  offers  advantages  in 
cleanliness  and  protection  of  the  movement,  such  clocks  have 
never  become  popular,  as  they  have  lost  their  character  as 
works  of  art  by  being  enclosed  in  plain  cases,  or  have  be- 
come rather  erratic  in  rate  by  the  substitution  of  springs 
for  weights. 

The  use  of  exposed  weights  and  pendulum  necessitates 
openings  in  the  bottom  of  the  case  through  which  the  dust 
enters  freely  and  this  makes  necessary  unusual  side  shake, 
end  shake  and  freedom  of  depthing  of  the  wheels  and  pin- 
ions and  also  the  use  of  lantern  pinions  and  an  amount  of 
driving  weight  in  excess  of  that  necessary  for  protected 
movements,  as  there  must  be  enough  weight  to  pull  the 

319 


320  THE    MODERN    CLOCK. 

cuckoo  movement  through  obstructions  which  would  stop 
the  ordinary  movement. 

Repairers  therefore  should  not  attempt  to  close  worn 
holes  as  snugly  as  in  the  ordinary  movements,  as  when  this 
is  done  the  clock  generally  stops  about  three  weeks  after  it 
has  left  the  shop  and  a  "comeback"  is  the  result.  Lighten- 
ing the  driving  weights  will  have  the  same  result,  as  the 
movement  must  have  sufficient  power  to  pull  it  through 
when  dirty.  As  the  plates  and  wheels  are  generally  of  cast 
metal,  cutting  of  pivots  from  running  dry  is  frequent  in 
old  clocks,  and  where  it  is  necessary  to  close  the  holes  care 
must  be  taken  not  to  overdo  it. 

Another  point  where  repairers  fail  is  in  not  polishing  the 
pivots.  Many  watchmakers  seem  to  think  that  any  kind 
of  a  pivot  will  do  for  a  clock,  although  they  take  great  care 
of  them  in  their  watchwork.  Rough  and  dry  pivots  will 
cut  the  holes  in  a  clock  plate  deep  enough  to  wedge  the 
pivots  in  the  holes  like  a  stuck  reamer  and  stop  a  clock 
just  after  it  has  been  repaired,  when  if  they  had  been  prop- 
erly polished  the  job  would  not  have  come  back. 

The  high  prices  of  wood  carving  in  America  and  the 
necessity  for  its  genuineness,  as  explained  above,  has  re- 
sulted in  making  it  necessary  to  spend  as  little  as  possible 
for  the  movements ;  hence  we  ordinarily  find  a  total  lack  of 
finish  on  the  movements,  and  this,  with  the  great  freedom 
everywhere  evident  in  its  construction  and  the  apparent 
excess  of  angular  motion  of  the  levers,  combine  to  give  it 
an  appearance  of  roughness  which  surprises  those  who  see 
them  but  rarely. 

It  has  been  frequently  suggested  by  watchmakers  that  if 
the  cases  only  were  imported  and  the  movements  were  made 
by  the  American  factories  better  results  should  be  obtained, 
in  appearance  at  least.  They  forget  that  the  bellows,  pipes 
and  birds,  with  their  wires,  are  parts  of  the  movements 
and  the  cost  of  having  these  portions  made  in  this  country 
is  prohibitive,   so  that  the   whole  movement  is   imported. 


THE    MODEIiN    CLOCK.  32  1 

Arrangements  are  now  being  made  by  at  least  one  firm  to 
have  the  frames  and  wheels  made  of  sheet  metal  by  auto- 
matic machinery,  instead  of  being  cast  and  finished  in  the 
usual  way,  and  when  this  is  done  the  appearance  of  the 
movements  will  be  greatly  improved,  so  that  American 
watchmakers  will  regard  them  with  a  more  kindly  eye. 
So  far  as  is  known  to  the  writer  all  cuckoo  movements  are 
im.ported,  although  one  firm  is  doing  a  large  and  constantly 
growing  trade  in  such  clocks  with  cases  made  in  America. 

There  are  a  number  of  importing  firms  who  sell  to  job- 
bers, large  retailers  and  clock  companies  only,  and  as  the 
large  American  clock  manufacturers  all  list  and  carry 
cuckoos  the  clocks  find  their  way  to  the  consumer  through 
many  and  devious  channels.  Probably  more  are  sold  in 
other  ways  than  through  the  retailers  for  the  reason  that 
the  average  retailer  does  not  understand  the  cuckoos  and 
is  reluctant  to  stock  them,  thereby  deliberately  avoiding  a 
large  amount  of  business  from  which  he  might  make  a 
haiidsome  profit. 

Under  the  general  term  Cuckoos  are  listed  several  kinds 
of  movements,  all  having  bellows,  pipes  and  moving  fig- 
ures, such  as  the  cuckoo,  cuckoo  and  quail,  trumpeter,  etc., 
with  or  without  the  regular  hammers  and  gongs  of  the  ordi- 
nary movements. 

Figs.  TOi  and  102  show  front  and  back  views  of  a  tmie 
train  in  the  center  with  quail  strike  train  on  the  left  and 
cuckoo  strike  train  at  the  right.  The  positions  of  arbors, 
levers,  depthings  of  trains,  etc.,  are  exact,  but  the  m.ove- 
ment  plates  have  been  left  off  for  greater  clearness,  so  that 
the  arbors  appear  to  be  without  support.  The  positions  of 
the  pillars  are  shown  by  the  shaded  circles  above  and  below 
the  trains  in  Fig.  loi.  The  parts  have  the  same  letters  in 
both  Figs.  ]Ci  and  102,  althoigh  as  the  movement  is  turned 
around  to  show  the  rear  in  102,  the  quail  train  appears  on 
the  right  side. 


322 


THE    MODERN    CLOCK. 


Fig.  101.    Front  View  of  Quail  and  Cuckoo  Strike  Movement. 


THE    MODEJiX    CLOCK. 


NAMES    OF    PARTS. 


3- 


A— Quail  count  wheel.  O— Quail  Lifting  pin  wheel. 

B— Quail  striking  cam.  P— Cuckoo  lifting  lever. 

C— r^liuute  wheel.  Q— Cuckoo  warning  lever. 

D— Quail  lifting  lever.  R— Cuckoo  lifting  pin. 

E— Quail  count  hook.  S— Cuckoo  locking  arm. 

F— Quail  locking  arm.  T— Cuckoo  count  hook. 

G— Quail  bird  stick;  U— Cuckoo  striking  cam. 

alpo  called  bird  holder.        V— Cuckoo  lifting  pin  wheel. 

H— Quail  bellows  arm.  W— Cuckoo  count  wlieel. 
I— Quail  bellows  lifting  lever.         X— Cuckoo  bellows  lifting  lever. 

J— Quail  gong  hammer.  Y — Cuckoo  hnnimcr. 

K— Quail  warning   lever.  Z— Cuckoo  biid  stick; 
L,— Quail  lifting  pin.  also  called  bird  holder. 

M— Quail  bird  stick  lever.  S^— Cuckoo  bird   stick  lever. 
iS  — Quail  hammer  lever. 

In  examining  a  movement  the  student  discovers  a  peculi- 
arity of  cuckoo  frames,  which  is  that  the  pivot  holes  for 
several  of  the  arbors  of  the  striking  levers  have  slots  filed 
into  them,  reaching  to  the  edges  of  the  frames  and  nar- 
rower than  the  full  diameter  of  the  pivot  holes.  This  is 
because  such  arbors  have  levers  riveted  into  them  which 
must  function  in  front,  between  and  at  the  rear  of  the  plates 
and  in  setting  up  the  movem.ent  the.  slots  are  necessary  to 
allow^  the  end  levers  to  pass  through  the  holes.  Such  arbors 
as  have  slots  on  the  front  plates  are  inserted  and  placed  in 
their  proper  positions  before  setting  the  train  wheels  wdth 
which  they  function.  The  others  are  first  inserted  in  the 
back  plate  and  turned  to  position  while  putting  on  that 
plate. 

Both  quail  and  cuckoo  trains  are  set  up  very  simply  and 
surely  by  observing  the  following  points :  In  the  quail 
train,  when  the  quail  bellows  lever,  H,  is  just  released  from 
a  pin  in  the  pin  wdieel,  O,  the  locking  lever,  F,  must  just 
fall  into  the  slot  of  the  locking  cam,  B;  the  warning  pin 
should  then  be  near  the  fly  pinion  and  the  count  hook,  K, 
drop  freely  into  the  count  wheel,  A. 

On  the  cuckoo  side  we  find  two  levers,  X ;  the  upper  one 
of  these  operates  the  low  note  of  the  cuckoo  call  and  the 
lower  one  the  high  note.    When  this  upper  lever  is  released 


324 


THE    MODERN    CLOCK. 


Fig.  102.    Rear  View  of  Quail  and  Cuckoo  Movement. 


THE    MODERN    CLOCK. 


3-5 


from  a  pin  in  the  pin  wheel,  the  cuckoo  locking  lever,  S. 
must  drop  into  its  locking  cam,  U,  and  the  count  hook,  T, 
drop  into  its  count  wheel,  while  the  warning  pin  must  be 
near  the  fly  pinion.  After  the  run  has  stopped  and  the 
trains  are  fully  locked  the  warning  pins  will  be  as  shown 
in  Fig.  102;  but  at  the  moment  of  locking  they  should  be 
as  described  above. 

The  operation  is  as  follows:  Turning  to  Fig.  loi,  we 
find  the  minute  wheel,  C.  has  four  pins  projecting  from  its 
rear  surface.  This  revolves  once  per  hour  and  conse- 
quently the  pins  raise  the  lifting  lever,  D,  every  fifteen 
minutes.  Here  is  a  point  that  frequently  is  productive  of 
trouble.  The  reader  will  readily  see  that  if  the  hands  of 
a  cuckoo  are  turned  backv/ard  the  pins  in  the  minute  wheel 
w^ill  bend  this  wire,  D,  and  derange  the  striking,  as  the 
warning  lever  is  also  attached  to  the  same  arbor.  Never 
push  the  hands  baekzvard  on  a  cuckoo  clock ;  ahvays  push 
them  forward.  If  the  striking  and  hands  do  not  register 
the  same  time,  take  off  the  weights  of  the  striking  trains ; 
then  push  the  hands  forward  until  they  register  the  hour 
which  the  trains  struck  last.  As  there  is  no  power  on  the 
trains  they  wdll  not  be  operated,  the  only  action  being  the 
rising  and  falling  of  the  lever,  D,  as  the  pins  pass.  When 
the  hands  point  to  the  hour  last  struck  by  the  trains,  put 
on  the  striking  weights  again  and  push  the  hands  forzi'ard, 
allowing  time  for  each  striking,  until  the  clock  has  been 
set  to  the  correct  time. 

Upon  the  lifting  lever,  D,  being  raised  sufficiently  the 
warning  lever,  E,  on  the  same  arbor  is  lifted  into  the  path 
of  the  warning  pin  and  at  the  same  time  unlocks  the  train 
by  pressing  against  the  lifting  pin,  L,  in  the  locking  lever, 
F.  The  locking  lever,  F,  count  hook,  K,  and  the  bird 
holder  lever,  M,  are  all  on  the  same  arbor  and  therefore 
work  in  unison.  When  D  drops,  E  releases  the  warning 
pin  and  the  train  starts.  The  pin  wdicel  has  pins  on  both 
sides,  the  rear  pins  operate  the  gong  hammer,  N,  J ;    the 


2--"  TJIE    ISIODERN    CI.OCK. 

front  pins  operate  the  quail  bellows,  I,  H.  The  rising,  and 
falling  of  the  unlocking  lever,  F,  operates  the  bird  holder, 
G,  through  M  and  the  wire  in  the  bellows  top  tilts  the  tail 
of  the  bird  and  flutters  the  wings.  When  the  fourth  quarter 
has  been  struck,  the  pins  shown  in  the  quail  count  wheel, 
A,  operate  the  hour  hfting  lever,  P,  and  the  action  of  that 
train  becomes  similar  to  that  of  the  quarter  train  just  de- 
scribed, with  the  difference  that  there  are  two  bellows 
levers,  X,  for  the  high  and  low  notes  of  the  cuckoo,  whereas 
there  is  but  one  for  the  quail. 

There  are  several  adjustments  necessary  to  watch  on 
these  clocks.  The  wires  to  operate  the  bellows  from  the 
levers  X  and  H  may  be  so  long  that  the  bellows  when 
stretched  to  its  full  capacity  may  not  allow  the  tails  of  X 
and  H  to  clear  the  pins  of  the  pin  wheels  and  thus  stop 
the  trains.  The  pins  should  clear  safely  w:th  the  bellows 
fully  opened.  The  levers  M  and  S',  which  operate  .he 
bird  holders,  G  and  Z,  may  be  turned  in  their  arbors  so  as 
to  be  farther  from  or  closer  to  the  bird  holder;  this  regu- 
lates the  opening  and  closing  of  the  doors  and  the  appear- 
ance of  the  birds ;  if  there  is  too  much  movement  the  birds 
may  be  sent  so  far  out  that  they  will  not  return,  but  will 
stay  out  and  stop  the  trains.  Moving  S'  and  M  towards 
the  bird  holders,  Z  and  G,  will  lessen  the  amount  of  this 
motion  and  the  contrary  movement  will  increase  it. 

Another  important  source  of  trouble — because  generally 
unsuspected — is  the  fly.  The  fly  on  a  cuckoo  train  must 
be  tight ;  a  loose  fly  will  cause  too  rapid  striking  and  allow 
tlic  train  to  overrun,  making  wrong  striking,  or  in  a  very 
bad. case  it  will  not  stop  until  run  down.  When  this  hap- 
pens turn  your  attention  to  the  fly  and  make  sure  that  it  is 
tight  before  doing  any  bending  of  the  levers,  and  also  see 
to  the  position  of  the  warning  pin. 

Sometimes  the  front  of  the  case  (which  is  also  the  dial) 
will  warp  and  cause  pressure  on  the  ends  of  the  lever  ar- 


THE    MODERN    CLOCK. 


3-7 


bors   and   thus   interfere   with   their   proper   working.      Be 
sure  that  the  arbors  are  free  at  both  ends. 

When  replacing  worn  pins  in  the  striking  trains,  care 
should  be  taken  to  get  them  the  right  length,  as  on  account 
of  the  large  amount  of  end  shake  in  these  movements  they 
may  slip  past  the  levers  w^ithout  operation,  if  too  short,  or 
foul  the  other  parts  of  the  train  if  too  long.  For  the  same 
reasons  bending  the  levers  should  only  be  done  after  ex- 
hausting the  other  sources  of  error  and  then  be  undertaken 
very  slowly  and  cautiously. 

The  notes  of  a  cuckoo  are  A  and  F,  jirst  belov/  middle  C ; 
these  should  be  sounded  clearly  and  with  considerable  vol- 
ume. If  they  are  short  and  husky  in  tone  it  may  be  due 
to  holes  in  the  bellow^s,  too  short  stroke  of  bellows,  removal 
of  the  bellows  weights,  E,  Fig.  103,  dirt  in  the  orifices  of  the 
pipes,  or  cracks  in  the  pipes.  Holes  in  the  bellows,  if  small 
and  not  in  the  folds  of  the  kid,  may  be  m.ended  by  being 
glued  up  with  paper  or  kid,  or  a  piece  of  court  plaster 
which  is  thin  enough  to  not  interfere  wi'di  the  operation  of 
the  bellow^s.  If  much  worn  a  new  bellow^s  should  be  sub- 
stituted.    Cracks  in  the  pipes  may  be  mended  with  paper. 

The  orifice  of  the  pipe,  if  dirty,  may  be  cleaned  with  a 
piece  of  mainspring  filed  very  thin  and  smooth  and  care- 
fully inserted,  as  any  widening  or  roughening  of  this  slit 
w^ill  interfere  with  the  tone.  Sometimes  a  clock  comes  in 
v;hich  has  been  spoiled  in  this  regard,  then  it  beconies  nee 
essary  to  remove  the  outer  portion  or  lip.  A,  Fig.  1 03,  of 
the  slot  (which  is  glued  in  position)  and  make  a  new  inner 
lip,  B,  or  file  the  old  one  smooth  again.  The  proper  shape 
is  shown  in  B,  Fig.  103,  while  C  and  D  show  improper 
shapes  which  interfere  with  the  tone. 

]\Iuch  time  and  money  has  been  spent  in  trying  to  avoid 
the  inherent  defects  of  this  portion  of  the  clock;  sometimes 
the  lips  will  swell  or  warp  and  close  the  orifice;  sometimes 
they  wdll  shrink  and  make  it  too  wide ;  in  either  case  a  loss 
of  purity  of  tone  is  the  result.     Brass  tubes,  if  thm  enougn 


328 


THE    MODERN    CLOCK, 


Fir:.  193.    Cuckoo  bellows  and  pipe.     A,  outer  lip;  B,   inner  lip;  C,  D, 
incorrect  forms  of  lip. 


THE    MODERN    CLOCK.  329 

to  be  cheap,  give  a  brassy  tone  to  the  notes ;  compositions 
of  lead,  tin  and  antimony  (organ  pipe  metal)  are  readily 
cast,  but  give  a  softer,  duller  tone  of  less  volume  than  the 
wood.  Celluloid  lips  to  a  wooden  tube  were  at  first  thought 
to  be  a  great  success,  but  were  found  to  warp  as  they  got 
older.  Bone  lips  are  costly ;  so  there  is  nothing  at  present 
that  seems  likely  to  displace  well  seasoned  wood,  where 
discriminating  lovers  of  music  and  art  demand  purity  and 
correctness  of  tone,  reasonably  accurate  time,  artistic  sculp- 
tural effects  and  durability,  all  in  one  article — a  high  class 
cuckoo  clock. 

When  sending  a  clock  home  after  repairing,  each  of  the 
chains  should  be  tied  together  with  strings  just  outside  the 
bottom  of  the  case  so  that  they  will  not  slip  off  the  sprockets 
and  the  customer  should  be  instructed  to  hang  the  clock 
in  its  accustomed  position  before  cutting  the  strings  and 
attaching  the  weights. 


CHAPTER  XVIII. 

SNAIL    STRIKING    WORK,    ENGLISH,    FRENCH    AND    AMERICAN. 

While  the  majority  of  snail  striking  movements  made  in 
America  are  on  the  French  system,  because  they  are  cheaper 
when  made  in  that  way,  still  this  system  is  so  condensed 
and  so  difficult  to  illustrate,  with  all  its  mechanism  packed 
in  a  small  space  between  the  plates,  that  the ,  student  will 
gain  a  much  better  idea  of  the  rack  and  snail  and  its  prin- 
ciples by  first  making  a  study  of  an  English  snail  striking 
clock,  which  has  the  whole  of  the  counting  and  releasing 
levers  placed  outside  the  front  plate,  where  they  can  occupy 
all  the  room  that  may  be  necessary.  The  calculation  and 
planting  of  the  striking  train  do  not  differ  from  those  using 
the  count  wheel,  up  to  and  including  the  single  toothed 
pinion  or  gathering  pallet.  The  stopping  of  the  train  after 
striking  is  different  and  the  counting  is  divided,  being  de- 
pendent upon  four  pieces  acting  in  conjunction  in  an  hour 
strike  of  the  simplest  order,  which  number  may  run  to  a 
dozen  in  a  repeating  clock. 

As  the  count  wheel  system  had  the  defect  of  getting  out 
of  harmony  with  the  hands  when  the  latter  are  turned  back- 
ward, so  the  snail  system  has  its  defects,  which  are  the  dis-. 
placement  of  the  rack  and  failure  to  stop  the  striking  in 
some  clocks  if  the  striking  train  runs  down  before  the  time 
side  and  is  then  rewound,  and  a  most  puzzling  inaccuracy 
of  counting,  resulting  from  slight  wear  and  inaccuracy  of 
adjustment.  We  mention  these  things  here  because  they 
have  an  influence  on  the  construction  of  the  clock  and  an 
advance  knowledge  of  them  will  serve  to  make  clearer  some 
of  the  statements  which  follow. 

330 


THE    MODERN    CLOCK.  33I 

Hour  and  Half-Hour  Snail  Striking  Work. — Fig. 
104  is  a  view  of  the  front  plate  of  an  English  fusee  strik- 
ing clock,  on  the  rack  principle.  The  going  train  occupies 
the  right  and  center  and  the  striking  train  the  left  hand. 
The  position  of  the  trains  is  indicated  in  dotted  lines,  the 
trains  having  barrels  and  fusees  as  shown  by  the  squared 
arbors,  all  the  dotted  work  being  between  the  clock  plates, 
and  that  in  full  lines  being  placed  on  the  outside  of  the 
front  plate,  under  the  dial.  The  connection  between  the 
going  train  and  the  striking  w^ork  is  by  means  of  the  motion 
w^ieel  on  the  center  arbor,  and  connection  is  made  between 
the  striking  train  and  the  counting  work  by  the  gathering 
pallet,  F,  wdiich  is  fixed  to  the  arbor  of  the  last  wheel  but 
one  of  the  striking  train,  and  also  by  the  warning  piece, 
which  is  shown  in  black  on  the  boss  of  the  lifting  piece,  A. 
This  w^arning  piece  goes  through  a  slotted  hole  in  the  plate, 
and  during  the  interval  between  warning  and  striking  stands 
in  the  path  of  a  warning  pin  in  the  last  wheel  of  the  striking 
train.  The  motion  wheel  on  the  center  arbor,  turning  once 
in  an  hour,  gears  with  the  minute  wheel,  E,  which  has  an 
equal  number  of  teeth.  There  are  tw^o  pins  opposite  each 
other  and  equidistant  from  the  center  of  the  minute  wheel, 
which  in  passing  raise  the  lifting  piece,  A,  every  half  hour. 
Except  for  a  few  minutes  before  the  clock  strikes,  the  strik- 
ing train  is  kept  from  running  by  the  tail  of  the  gathering 
pallet.  F,  resting  on  a  pin  in  the  rack,  C.  Just  before  the 
hour,  as  the  boss  of  the  lifting  piece,  A,  lifts  the  rack  hook 
B,  the  rack  C,  impelled  by  a  spring  in  its  tail,  falls  back 
until  the  pin  in  the  lower  arm  of  the  rack  is  stopped  by  the 
snail,  D.  This  occurs  before  the  lifting  piece,  A,  is  released 
by  the  pin  in  the  minute  wheel,  E,  and  in  this  position  the 
warning  piece  stops  the  train.  Exactly  at  the  hour  the  pin 
in  the  minute  wheel,  E,  gets  past  the  lifting  piece,  A,  wdiich 
then  falls,  and  the  train  is  free.  For  every  blow  struck  by 
the  hammer  the  gathering  pallet,  F,  which  is  really  a  one- 
toothed  pinion,  gathers  up  one  tooth  of  the  rack,  C,  which 


332  THE    MODERN    CLOCK. 

is  then  held,  tooth  by  tooth,  by  the  point  of  the  hook,  B. 
After  the  pinion,  F,  has  gathered  up  the  last  tooth,  its  tail  is 
caught  by  the  pin  in  the  rack,  which  stops  and  locks  the 
tram,  and  the  striking  ceases. 

The  snail,  O,  is  mounted  on  a  twelve-toothed  star  wheel, 
placed  on  a  stud  in  the  plate,  so  that  a  pin  in  the  motion 
wheel  on  the  center  arbor  moves  it  one  tooth  for  each  revo- 
lution of  the  motion  wheel,  and  it  is  then  held  in  position  by 
the  click  and  spring  as  shown.  The  pin,  in  moving  the  star 
wheel,  presses  back  the  click,  which  not  only  keeps  the 
star  wheel  steady,  but  also  completes  its  forward  motion 
after  the  pin  has  pushed  the  tooth  past  the  projecting  center 
of  the  click.  The  steps  of  the  snail  are  arranged  so  that  at 
one  o'clock  it  permits  only  sufficient  fall  of  the  rack  for  one 
tooth  to  be  gathered  up,  and  at  every  succeeding  hour  gives 
the  rack  an  additional  motion  equal  to  one  extra  tooth.  It 
will  be  seen  that  where  a  star  wheel  is  used  a  cord  or  wire 
attached  to  A  and  run  outside  the  case,  so  that  A  may  be 
lilted,  will  cause  the  clock  to  repeat  the  hour  whenever 
desired. 

The  lower  arm  of  the  rack,  C,  and  the  lower  arm  of  the 
lifting  piece.  A,  are  made  of  brass,  and  thin,  so  as  to  yield 
when  the  hands  of  the  clock  are  turned  back ;  the  lower 
extremity  of  the  lifting  piece.  A,  is  a  little  wider,  and  bent 
to  a  slight  angle  with  the  plane  of  the  arm,  so  as  not  to  butt 
as  it  comes  into  contact  with  the  pin  when  this  is  being 
done.  If  the  clock  is  not  required  to  repeat,  the  snail  may 
be  placed  upon  the  center  arbor,  instead  of  on  a  stud  with 
a  star  wheel  as  shown,  and  this  is  generally  done  with  the 
che::per  class  of  hour  striking  clocks ;  but  the  position  of  the 
snail  is  not  then  so  definite,  owing  to  the  backlash  of  the 
motion  wheels,  so  that  it  will  not  repeat  correctly,  as  the 
pin  of  the  rack  m,ay  fall  on  a  slope  of  the  snail  and,  besides, 
a  smaller  snail  must  be  used,  unless  it  is  brought  out  to 
clear  the  nose  of  the  minute  wheel  cock,  or  bridge  if  one 
be  used. 


THE    MODERN    CLOCK. 


333 


..^^^P^^^^ 


Fig.  104.     Hour  and  half  hour  snail  striking  work  "with  fusee  train. 


334 


THE    MODERN    CLOCK. 


Half-Hour  Striking. — The  usual  way  of  getting  the 
clock  to  strike  one  at  the  half-hour,  is  by  making  the  first 
tooth  of  the  rack,  C,  lower  than  the  rest,  and  placing  the 
second  pin  in  the  minute  wheel,  E,  a  little  nearer  the  center 
than  the  hour  pin,  so  that  the  rack  hook,  B,  is  lifted  free 
of  the  first  tooth  only  at  the  half  hour.  But  this  adjustment 
is  too  delicate  after  some  wear  has  occurred  and  the  action 
is  then  liable  to  fail  altogether  or  to  strike  the  full  hour, 
from  the  pin  getting  bent  or  from  uneven  wear  of  the  parts. 
The  arrangement  shown  in  Fig.  104  is  generally  used  in 
English  work,  as  it  is  much  safer.  One  arm  of  a  bell  crank 
lever  rests  on  a  cam  fixed  to  the  minute  wheel,  E.  This 
arm  is  shaped  so  that  just  before  the  half-hour  the  other  ex- 
tremity of  the  bell  crank  lever  catches  a  pin  placed  in  the 
rack,  C,  and  permits  it  to  release  the  train  and  fall  the  dis- 
tance of  but  one  tooth.  This  is  the  position  shown  in  Fig. 
104.  After  the  half-hour  has  struck,  the  cam  carries  the 
hook  free  from  the  pin  in  C. 

Division  of  the  Hour  Snail.— The  length  of  the  rack 
tail,  from  the  center  of  the  stud  hole  in  the  rack  to  the 
center  of  the  pin,  should  be  equal  to  the  distance  between 
the  center  of  the  stud  hole  and  the  center  of  the  snail.  The 
difference  between  the  radius  of  the  top  and  the  radius  of 
the  bottom  step  of  the  snail  may  be  obtained  by  getting  the 
angular  distance  of  twelve  teeth  of  the  rack  from  center  to 
pin.  See  A  B,  CD,  E  F,  Fig.  105,  which  show  the  total 
distances  for  twelve  steps  of  the  snail  for  rack  tails  of 
different  lengths.  Divide  the  circumference  of  a  piece  of 
brass  into  twelve  parts  and  draw  radial  lines  as  shown  in 
Fig.  106.  Each  of  these  spaces  is  devoted  to  a  step  of  the 
snail.  Draw  circles  representing  the  top  and  bottom  step. 
Divide  the  distance,  A  B  or  E  F,  Fig.  105,  between  these 
two  circles,  into  eleven  equal  parts,  and  at  each  division 
draw  a  circle  which  will  represent  a  step  of  the  snail.  The 
rise  from  one  step  to  another  should  be  sloped  as  shown,  so 
as  to  raise  the  pin  in  the  rack  arm  if  the  striking  train  has 


THE    MODERN    CLOCK. 


335 


been  allowed  to  run  down,  and  it  should  be  resting  on  the 
snail  when  it  is  desired  to  turn  the  hands  back.  The  rise 
from  the  bottom  to  the  top  step  is  bevelled  off,  so  as  to  push 
the  pin  in  the  rack  arm  on  one  side,  by  springing  the  thin 
brass  of  the  arm  and  allow  it  to  ride  over  the  snail  if  it  is 
in  the  way  when  the  clock  is  going.  It  should  also  be 
curved  to  avoid  interference  with  the  pin.  Clockmakers 
making  new  snails  when  repairing  generally  mark  off  the 


Fig.  105.    Rack,  showing  method  of  getting  sizes  of  snail  steps   accord- 
ing to  distance  from  the  rack  center  to  the  pin  in  the  rack  tail. 


snail  on  the  clock  itself  after  the  rest  of  the  striking  work 
is  in  position.  A  steel  pointer  is  fixed  in  the  hole  of  the 
lower  rack  arm,  and  the  star  wheel  jumped  forward  twelve 
teeth  (one  at  a  time)  by  means  of  the  pin  in  the  motion 
wheel.  After  each  jump  a  line  is  marked  on  the  blank 
snail  with  the  pointer  in  the  rack  arm  by  moving  the  rack 
arm.  These  twelve  lines  correspond  to  the  twelve  radial 
lines  in  Fig.  io6.  The  motion  wheel  is  then  turned  suffi- 
ciently to  carry  the  pin  in  it  free  of  the  star  wheel  and 
leave  the  star  wheel  and  blank  snail  quite  free  on  their  stud. 
The  rack  hook  is  placed  in  the  first  tooth  of  the  rack,  and 
v^hile  the  pointer  in  the  rack  arm  is  pressed  on  the  blank 
snail,  the  latter  is  rotated  a  little,  so  that  a  curve  is  traced 
on  it.    The  rack  hook  is  then  placed  in  the  second,  and  after- 


336  THE    MODERN    CLOCK. 

wards  in  the  succeeding  teeth  consecutively,  and  the  opera- 
tion repeated  till  the  twelve  curves  are  marked.  There  is 
one  advantage  in  marking  off  the  snail  in  this  way.  Should 
there  be  any  inaccuracy  in  the  division  of  the  teeth  of  the 
rack,  the  steps  of  the  snail  are  thus  varied  to  suit  it.  This 
frequently  occurs  in  old  clocks  which  have  had  new  racks 
filed  up  by  hand  by  some  watchmaker. 

Reference  to  the  drawing.  Fig.  105,  will  show  that  the 
rack  is  laid  out  as  a  segment  of  a  wheel  with  teeth  occupy- 
ing two  degrees  each,  with  a  few  teeth  added  for  safety. 
Fourteen  to  sixteen  teeth  are  generally  provided,  for  the 
following  reasons :  If  the  first  tooth  is  used  to  strike  the 
half  hours,  it  may  in  time  become  worn  so  that  it  can  no 
longer  be  stretched  to  its  proper  length.  In  such  cases 
moving  the  pin  two  degrees  nearer  the  rack  teeth  will  allow 
us  to  use  the  teeth  from  the  second  to  the  thirteenth  in 
striking  twelve,  which  makes  a  cheap  and  easy  repair,  as 
compared  to  inserting  a  new  tooth  or  making  a  new  rack. 

Weight  driven  snail  clocks  should  have  the  weight  cords 
of  the  striking  side  long  enough  so  that  the  striking  train 
will  not  run  down  before  the  time  train,  as  in  such  a  case 
the  rack  tail  is  pushed  to  one  side  by  the  progress  of  the 
snail  (which  is  carried  on  the  time  train  and  is  still  run- 
ning) ;  then  the  rack  will  drop  clear  out  of  reach  of  the 
gathering  pallet  and  when  the  striking  train  is  wound  that 
train  will  continue  striking  until  it  runs  down,  or  the  dial 
is  removed  and  the  rack  replaced  in  mesh  with  the  gather- 
ing pallet.  This  happens  with  short  racks  and  with  large, 
old-fashioned  snails.  By  leaving  a  few  more  teeth  in  the 
rack  the  rack  tail  will  strike  the  stud,  or  hour  wheel  sleeve, 
before  the  rack  teeth  get  out  of  reach  of  the  gathering 
pallet. 

Many  watchmakers  put  a  stud  or  pin  in  the  plate  to  stop 
the  rack  from  falling  beyond  the  twelfth  step,  to  prevent 
troubles  of  this  kind. 


THE    MODERN    CLOCK. 


337 


The  rack  tail  is  friction-tight  on  its  arbor  and  should  be 
adjusted  so  that  the  proper  tooth  shall  come  in  mesh  with 
the  gathering  pallet  for  each  step  of  the  snail,  or  irregular 
striking  will  result.  Such  a  clock  may  strike  one,  two,  three 
and  four  correctly  and  then  strike  six  for  five,  or  seven  or 
nine  for  eight,  or  thirteen  for  twelve,  or  it  may  strike  one 
or  two  hours  wrong  and  the  rest  correctly.  This  is  be- 
cause the  gathering  pallet,  F,  Fig.  104,  does  not  carry  the 


rack  teeth  safely  past  the  edge  of  the  rack  hook,  B,  owing 
to  the  tail  of  the  rack  not  being  properly  adjusted.  The 
teeth  should  all  be  carried  safely  past  the  edge  of  the  hook 
and  then  be  dropped  back  a  little  as  the  hook  engages ;  this 
is  the  more  necessary  to  watch  with  hand-made  racks  and 
snails,  or  after  putting  in  a  new,  and  therefore  larger,  pin 
in  the  rack  tail  to  replace  one  which  is  badly  worn. 

The  snail  should  be  put  on  so  that  the  pin  in  the  rack 
tail  will  strike  the  center  of  each  step,  or  there  is  danger  of 
irregular  striking,  or  of  failure  to  strike  twelve,  owing  to 
the  pin  striking  the  surface  of  the  cam  midway  between 
one  and  twelve  and  thus  preventing  the  rack  from  falling 


33^  THE    MODERN    CLOCK. 

the  requisite  number  of  teeth.  When  this  occurs  the  clock 
will  jam  and  stop. 

The  rack  hook,  B,  Fig.  104,  should  be  lifted  far  enough 
so  that  the  rack  will  fall  clear  of  the  hook  without  the  teeth 
catching  and  making  a  rattling  noise  as  they  pass  the  hook. 
In  many  old  hour  strikes  the  first  tooth  of  the  rack  is  left 
longer  than  the  rest  to  ensure  this  freedom  of  passage 
when  the  rack  is  released. 

The  gathering  pallet,  F,  is  the  weakest  member  of  the 
system  and  will  be  very  Hkely  to  be  split  or  worn  out  in 
clocks  brought  in  for  repair.  It  should  be  squared  on  its 
arbor,  or  pinned,  but  many  are  not.  If  split,  and  the  arbor  is 
round,  where  the  pallet  is  put  on,  it  may  cause  irregular 
striking  by  opening  on  the  arbor  and  permitting  the  train 
to  run  when  the  tail  strikes  the  pin  in  the  rack.  A  new  one 
should  be  made  so  as  to  lift  one  tooth  and  a  very  little  of 
the  next  one  at  each  revolution.  It  is  necessary  to  cause 
the  gathering  pallet  to  lift  a  little  more  than  one  tooth  of  the 
rack,  and  let  it  fall  back  again,  to  insure  that  one  will  always 
be  lifted;  because  if  such  was  not  the  case  the  clock  would 
strike  irregularly,  and  would  also  be  liable  sometimes  to 
strike  on  continually  till  it  ran  down.  If  the  striking  part  is 
locked  by  the  tail  of  the  gathering  pallet  catching  on  a  pin 
in  the  rack,  the  tail  should  be  of  a  shape  that  will  best  pre- 
vent the  rack  from  falling  back  when  the  clock  wcirns  for 
striking  the  next  hour ;  and  of  course  the  acting  faces  of  the 
pallet  must  be  perfectly  smooth  and  polished. 

The  teeth  of  the  rack  may  require  dressing  up  in  some 
cases  and  to  allow  this  to  be  done  the  rack  may  be  stretched 
a  little  at  the  stem,  with  a  smooth-faced  hamm.er,  on  a 
smooth  anvil ;  or,  if  it  wants  much  stretching,  take  the 
pene  of  the  hammer  and  strike  on  the  back,  with  the -front 
lying  on  the  smooth  anvil.  The  point  of  the  rack  hook,  B, 
will  probably  be  much  worn,  and  when  dressing  it  up  it 
will  be  safe  to  keep  to  the  original  shape  or  angle.  The 
point  of  the  rack  hook  is  always  broader  than  the  rack,  and 


THE    MODERN    CLOCK.  339 

the  mark  worn  in  it  will  be  about  the  middle  of  the  thick- 
ness ;  so  enough  will  be  left  to  show  what  the  original  shape 
or  angle  was. 

After  cleaning,  particularly  if  it  be  French,  look  for  dots 
on  the  rims  of  the  wheels,  and  for  pinions  with  one  end 
of  one  leaf  filed  ofif  slantingly.  When  putting  it  together, 
place  the  pin  wheel  (that  is  the  one  with  the  pins)  and  the 
pinion  it  engages  with  so  that  the  leaf  of  the  pinion  (which 
you  will  find  filed  slanting  at  one  extremity)  enters  be- 
tween the  two  teeth  of  the  wheel,  opposite  which  you  will 
find  a  countersunk  mark,  on  the  side  of  the  wheel.  See  also 
that  the  gathering  pallet,  F,  w^hich  lifts  the  rack,  does  so 
■at  the  same  time  that  the  gong  hammer  falls.  Then  place 
the  hour  and  minute  wheels  and  cannon  pinion  so  that  the 
countersunk  marks  on  each  line  with  each  other.  Neglect 
of  the  marks  on  a  marked  train  generally  means  that  you 
will  have  to  take  the  clock  down  again  and  set  it  up  prop- 
erly before  it  will  run ;  therefore  pay  attention  to  these 
marks  the  first  time. 


Quarter  Chiming  Snail  Strikes. — Fig.  107  shows  the 
counting  mechanism  and  trains  of  an  English,  fusee,  quar- 
ter-strike work.  The  time  train  occupies  the  center,  the 
hour  striking  train  the  left  and  the  chiming  train  the  right. 
All  the  train  wheels  are  between  the  plates  and  are  dotted 
in  as  in  Fig.  104,  while  the  counting  mechanism  is  on  the 
front  plate,  behind  the  dial  and  is  drawn  in  full  lines,  to 
show  that  it  is  outside. 


GOING  TRAIN. 

Fusee    Wheel 96 

Pinion    8 

Center   Wheel 84 

Pinion 7 

Tliird  Wheel 78 

Pinion 7 


340  THE    MODERN    CLOCK. 

STRIKING   TRAIN. 

Fusee  Wheel 84 

Pinion    8 

Pin  Wheel,  8  pins  in  Pin  Wheel 64 

Pinion    8 

Pallet    Wheel 70 

Pinion    7 

Warning    Wheel 60 

Fly   Pinion 7 

CHIMING  TRAIN. 

Fusee    Wheel 100 

Pinion 8 

Second    Wheel 80 

Pinion 8    • 

Pallet    Wheel ' 64 

Pinion    8 

Chiming    Wheel 40 

Warning  Wheel 50 

Fly  Pinion 8 

The  reader  will  see  a  marked  resemblance  between  the 
hour  and  time  trains  of  Fig.  104  and  the  same  trains  of 
Fig.  107.  The  hour  rack  hook  in  107,  however,  is  hung 
from  the  center  and  the  hour  warning  lever  is  raised  by  a 
spring  instead  of  a  Hfting  piece. 

The  minute  wheel  of  Fig.  107  carries  a  snail  of  four 
steps,  corresponding  to  the  four  teeth  of  the  quarter  rack, 
and  the  tail  of  the  quarter  rack  is  bent  upwards  towards  the 
rack,  to  engage  with  the  quarter  snail.  The  quarter  rack 
carries  a  pin  which  projects  on  both  sides  of  the  rack;  one 
side  of  this  pin  stops  the  tail  of  the  quarter  gathering  pallet 
and  therefore  locks  the  train  as  fully  described  in  Fig.  104. 
The  other  side  of  the  same  pin  acts  on  the  tail  of  the  hour 
warning  lever,  so  that  whenever  the  quarter  rack  falls  the 
hour  warning  lever  is  released  and  its  spring  moves  it  into 
the  path  of  the  hour  warning  pin.  This  goes  on  whether 
the  hour  rack  hook  is  released  or  not.  Behind  the  quarter 
snail,  there  are  four  pins  in  the  minute  wheel ;    these  pins 


THE    MODERN    CLOCK. 


341 


Fig.  107.    Quarter  chiming  snail  strike,  Englisli  fusee  movement. 


342 


THE    MODERN    CLOCK. 


raise  the  quarter  lifting  piece,  which  raises  the  quarter 
rack  hook  and  the  quarter  warning  lever  at  the  same  time, 
thus  warning  and  dropping  the  quarter  rack;  as  soon  as 
the  lifting  piece  drops,  the  warning  lever  and  rack  hook 
are  released  and  the  quarter  train  starts. 


Fig.  108.    Eight  day  snail  half  hour  strike,  French  system,  striking 
train  locked. 


One,  two,  three,  or  four  quarters  are  chimed  according 
to  the  position  of  the  quarter  snail,  wdiich  turns  with  the 
minute  wheel.  At  the  time  for  striking  the  hour  (when 
the  quarter  rack  is  allowed  to  fall  its  greatest  distance),  the 
pin  in  it  falls  against  the  bent  arm  of  the  hour  rack  hook, 
and  releases  the  hour  rack  and  hour  w^arning  lever.  As  the 
last  tooth  of  the  quarter  rack  is  gathered  up,  the  pin  in  the 
quarter  rack  pulls  over  the  hour  warning  lever,  and  lets  off 


THE    MODERN    CLOCK.  343 

the  hour  striking  train.  The  position  of  the  pieces  in  the 
drawing  is  as  they  would  be  directly  after  the  hour  was 
struck. 

Figs.  108,  109  and  no  arc  three  views  of  the  New 
Haven  eight-day  snail  strike,  which  is  on  the  French  sys- 
tem. As  nearly  all  American  strikes  utilize  this  system  and 
the  work  is  between  the  plates,  this  may  be  considered  a 
typical  American  snail  strike. 

As  will  be  seen  in  Fig.  io8,  by  the  two  pins  at  the  center 
arbor,  immediately  behind  the  snail,  this  is  a  half-hour 
strike ;  and  as  the  rack  hook  has  for  its  lower  step  a  little 
more  than  twice  the  depth  of  the  other  steps  in  the  snail,  it 
will  readily  be  perceived  that  this  rack  hook  may  be 
pushed  almost  out  and  thus  release  the  train  without  drop- 
ping the  rack.  This  is  the  method  pursued  in  striking  half 
hours. 

Figs.  109  and  no  show  the  parts  more  clearly  than  in 
108.  They  are  drawn  a  little  larger  than  actual  size  and 
wc  will  discover  that  the  rack  is  the  only  portion  of  this 
system  that  vrorks  by  gravity,  all  the  others  being  spring 
operated.  Wc  sec  here  the  pins  J  K,  which  are  used  to 
push  out  the  lever  M  sufficiently  far  so  that  the  upper 
portion,  which  is  bent  at  right  angles  to  form  a  stop,  will 
free  the  warning  pin  O  and  allow  the  train  to  run.  The 
rack  hook  and  the  locking  lever  L  are  mounted  on  the  same 
arbor  and  are  kept  in  position  by  a  coiled  spring  on  the 
arbor  until  they  are  pushed  out  by  the  lower  projection 
at  the  upper  end  of  M  for  either  the  half-hour  or  hour 
strike. 

As  shown  in  Fig.  109,  the  lever  M  and  the  rack  hook  are 
pushed  out  by  J  far  enough  to  pass  the  warning  pin  O  and 
to  unlock  the  train,  which  is  normally  locked  by  the  pin  N 
and  the  lever  L.  G  is  the  gathering  pallet,  which  is  a  long 
pin  in  a  lantern  pinion  as  in  the  ordinary  count  wheel  strike. 
H  is  the  hammer  tail  and  P  the  pin  wheel ;  R  is  the  rack  and 
T  the  rack  tail.    The  rack  arm  is  curved  to  pass  the  center 


344  THE    MODERN    CLOCK, 

arbor  when  dropping  for  twelve  and  the  rack  tail  is  bent 
toward  the  teeth  in  order  that  it  may  admit  of  a  longer  rack 
in  a  small  movement,  thus  permitting  of  a  large  snail 
and  consequently  less  liability  of  disarrangement.  The 
same  necessity  of  the  proper  adjustment  of  the  rack  tail  T 
with  the  snail  exists  as  has  already  been  spoken  of  in  regard 
to  the  English  form  of  the  snail  strike. 

In  Fig.  no  will  be  seen  the  rack  dropped  clear  with  the 
tail  resting  clear  of  the  snail  at  one  stroke  from  the  snail. 
In  other  words,  the  train  is  now  in  position  to  give  eleven 
more  strokes,  having  struck  the  first  stroke  of  twelve.  By 
comparison  with  Fig.  109,  it  will  be  seen  that  the  spring 
actuated  arm  M  has  been  thrown  forward  so  that  its  doc:  is 
resting  on  the  center  arbor,  after  having  been  released  from 
the  hour  pin  K.  This  holds  M  out  of  the  way  of  the  w^arn- 
ing  pin  O  and  the  rack  hook  and  allows  the  parts  to  oper- 
ate as  fully  described  with  the  English  rack. 

The  gathering  pallet  G  must  have  as  many  teeth  as  there 
are  teeth  between  the  pins  in  the  pin  wheel  P.  The  train 
is  locked  by  L  coming  in  contact  with  X,  the  locking  pin 
on  the  wheel  on  the  same  arbor  as  the  gathering  pallet.  In 
setting  this  train  up.  it  should  stop  so  that  the  warning  pin 
O  should  be  near  the  fly. 

As  all  the  parts  are  operated  by  springs  on  the  arbor,  as 
shown  by  the  hammicr  spring  II,  it  wi.l  be  seen  that  this 
strike  mechanism  will  wcrk  in  any  position,  while  that 
w^hich  is  operated  by  gravity  must  be  kept  upright.  A 
loose  fly  will  cause  the  clock  to  strike  too  fast  and  may 
cause  it  to  strike  wrong.  Careless  adjustment  of  the  rack 
tail  T  with  the  snail  will  also  induce  wrong  counting, 
although  this  is  somewhat  easier  to  adjust  than  the  English 
form  of  strike.  The  hock  should  safely  clear  the  rack 
teeth  just  as  the  gathering  pallet  G  lets  go  of  a  tooth.  If 
attention  is  paid  to  this  point  in  adjusting  the  rack  tail 
there  will  generally  be  little  trouble. 


THE    MODERX    CLOCK. 


3^5 


The  cam  bearing  the  pins  J  K  on  the  center  arbor  may  be 
shifted  with  a  pair  of  pliers  to  secure  accurate  register  of 
hands  and  strike,  as  is  the  case  with  most  American  strikes. 
In  putting  in  the  pin  wheel  it  should  be  set  so  that  the  pins 
may  have  a  little  run  be  fere  striking  the  hammer  tail,  as 


Fig.  109.  Train  about  to  strike  the  half  hour;  the  hook  1/ free  of  the 
train,  which  is  held  by  the  warning  pin  O  ;  one  stroke  will  be  given 
when  M  drops. 


this  hammer  tail  is  very  short,  and  if  the  spring  is  strong 
the  pins  may  not  be  able  to  lift  the  hammer  tail  without 
sufficient  run  to  get  the  train  thoroughly  under  motion. 
The  half-hour  strike  should  also  be  tested  so  that  the  pin  J 
will  release  the  warning  pin  O  from  the  lever  M  without 
releasing  the  rack  hook  from  the  rack,  as  shown  in  Fig. 


346 


THE    MODERN    CLOCK. 


109.  The  parts  of  the  train  when  at  rest  will  be  readily 
discerned  in  Fig.  108,  where  the  hook  L  has  locked  the 
train  by  the  pin  N  and  the  freedom  between  the  pins  and 
the  hammer  tail  is  about  what  it  should  be. 


Fig.  110.    Train  unloclted  and  running.     Xote  position  of  L  and  M. 


The  relative  position  of  the  locking  lever  L  and  the  rack 
hook  is  also  very  clearly  shown  in  Fig.  108;  that  is,  when 
the  rack  hook  is  pressed  clear  home  at  the  lower  notch  of 
the  rack,  the  lever  L  should  safely  lock  the  train  and  the 
lever  M  be  resting  with  its  link  against  the  center  arbor. 


CHAPTER   XIX. 

THE    CONSTRUCTION    OF   SIMPLE   AND   PERPETUAL    CALENDARS. 

In  taking  up  the  study  of  calendar  work  the  first  thing 
that  the  student  observes  is  the  irregularity  of  motion  of 
the  various  members.  Every  other  portion  of  a  clock  has 
for  its  main  object  the  attainment  of  the  nicest  regularity 
of  motion,  while  the  calendar  must  necessarily  have  irreg- 
ular motion.  The  hand  of  the  day  of  the  month  proceeds 
around  its  dial  regularly  from  i  to  28  and  then  jumps  t^ 
I  in  February  of  some  years,  while  it  continues  to  29  iii 
others;  sometimes  it  revolves  regularly  from  I  to  31  for 
several  revolutions  and  then  jumps  from  30  to  i.  What  is 
the  reason  of  this? 

If  the  moon's  phases  are  shown  they  do  not  agree  with 
the  changes  of  the  month  wheels,  but  keep  gaining  on  them, 
while  if  an  "equation  of  time"  is  shown,  we  have  a  hand 
that  moves  irregularly  back  and  forth  from  the  Figure  XII 
at  the  center  of  its  dial.  What  is  the  cause  of  this  gaining 
and  losing? 

In  order  to  understand  this  mechanism  properly  we  shall 
have  to  first  know  what  it  is  intended  to  show  and  this 
brings  us  to  the  study  of  the  various  kinds  of  calendar. 

The  earth  revolves  about  its  axis  with  a  circular  motion; 
it  revolves  about  the  sun  with  an  elliptical  motion.  This 
means  that  the  earth  will  move  through  a  greater  angular 
distance,  measured  from  the  sun's  center,  in  a  given  time  at 
some  portions  of  its  journey  than  it  will  do  at  others;  at 
times  the  sun  describes  an  arc  of  57  minutes  of  the  ecliptic ; 
at  other  times  an  arc  of  61  minutes  in  a  day;  hence  the  sun 
will  be  directly  over  a  given  meridian  of  the  earth  (noon) 

347 


348  THE    MODERN    CLOCK. 

a  little  sooner  at  some  periods  than  at  others.  Now  the 
time  at  which  the  sun  is  directly  over  the  given  meridian  is 
apparent  noon,  or  solar  noon.  As  before  stated,  this  is  ir- 
regular, while  the  motion  of  our  clocks  is  regular,  conse- 
quently the  sun  crosses  the  meridian  a  little  before  or  a 
little  after  twelve  by  the  clock  each  day,  varying  from  15 
minutes  before  twelve  to  15  minutes  after  twelve  by  the 
clock.  The  best  we  can  do  under  these  circumstances  is  to 
divide  these  differences  of  gaining  or  losing,  take  the  aver- 
age or  mean  of  them  and  regulate  the  clock  to  keep  mean 
time.  Here  then  we  have  two  times — the  irregular  appar- 
ent time  and  the  regular  mean  apparent  time.  The  amount 
to  be  added  to  or  subtracted  from  the  mean  in  order  to  get 
the  solar  or  actual  apparent  time  is  called  the  equation  of 
time  and  this  is  shown  by  the  equation  hand  on  an  astro- 
nomical or  perpetual  calendar  clock. 

The  moon  revolves  on  its  axis  with  a  circular  motion  and 
it  revolves  about  the  earth  with  an  elliptical  motion,  the 
earth  being  at  one  focus  of  the  ellipse ;  as  this  course  does 
not  agree  with  that  of  the  sun,  but  is  shorter,  it  keeps  gain- 
ing so  that  the  lunar  months  do  not  agree  with  the  solar. 

Certain  stars  are  so  far  away  that  they  apparently  have 
no  m.otion  of  their  own  and  are  called  iixed;  hence  in  ob- 
serving them  the  only  motion  we  can  discern  is  the  circular 
m^oticn  of  the  earth.  We  can  set  our  clocks  by  watching 
such  stars  and  a  complete  revolution  of  the  earth,  measured 
by  such  a  star,  is  called  an  asfronomieal  or  siderial  'day. 
This  is  the  one  used  in  computing  all  our  time.  It  is  shorter 
than  the  mean  solar  .day  by  3  minutes  56  seconds. 

A  year  is  defined  as  the  period  of  one  complete  revolu- 
tion of  the  earth  about  the  sun,  returning  to  the  same  start- 
ing point  in  the  heavens.  By  taking  different  starting 
points  we  are  led  to  different  kinds  of  years.  The  point 
generally  taken  is  the  vernal  equinoctial  point,  and  when 
measured  thus  it  is  called  the  tropical  year,  which  gives  us 
the  seasons.    It  is  20  mjnutes  shorter  than  the  siderial  year. 


THE    MODERN    CLOCK.  349 

A  siderial  year  is  the  period  of  a  complete  revolution 
of  the  earth  about  the  sun.  This  period  is  very  approxi- 
mately 365  days,  6  hours,  9  minutes,  9.5  seconds  of  mean 
time.  Here  we  see  an  important  difference  between  the 
siderial  and 'the  cio'il  year  of  365  days,  and  it  is  this  dif- 
ference, which  must  be  accounted  for  someliow,  that  causes 
the  irregularities  in  our  calendar  work. 

For  ordinary  and  business  purposes  the  public  demands 
that  the  year  shall  contain  an  exact  number  of  days  and 
that  it  should  bear  a  simple  relation  to  the  recurrence  of  the 
seasons.  For  this  reason  the  civil  year  has  been  introduced. 
The  Roman  emperor,  Julius  Caesar,  ordered  that  three  suc- 
cessive years  should  have  365  days  each  and  the  fourth^ 
year  should  have  366  days. 

The  fourth  year,  containing  366  days,  is  called  a  leap 
year,  because  it  leaps  over,  or  gains,  the  difference  between 
the  civil  and  siderial  time  of  the  preceding  three  years.  For 
convenience  the  leap  year  was  designated  as  any  year  whose 
number  is  exactly  divisible  by  4.  This  is  called  the  Julian 
calendar. 

But  as  a  siderial  year  is  365  days,  6  hours,  9  minutes, 
9.5  seconds  of  mean  time,  the  addition  of  one  day  of  twen- 
ty-four hours  would  not  exactly  balance  the  two  calendars ; 
therefore  Pope  Gregory  XIIL,  in  1582,  ordered  that  every 
year  whose  number  is  a  multiple  of  100  shall  be  a  year  of 
365  days,  unless  the  number  of  the  year  is  divisible  by  400, 
when  it  shall  be  a  leap  year  of  366  days. 

The  calendar  constructed  in  this  way  is  called  the  Gre- 
gorian calendar,  and  is  the  one  in  common  use.  Its  error 
is  very  small  and  will  amount  to  only  i  day,  5  hours,  30 
minutes  in  4,000  years. 

The  revolution  of  the  moon  around  the  earth  in  relation 
to  the  stars,  takes  place  in  2"/  days,  7  hours  and  43  minutes ; 
this  is  called  a  siderial  month.  But  during  this  period  the 
earth  has  advanced  along  the  plane  of  its  path  about  the  sun 
and  the  moon  must  make  up  this  distance  in  order  to  re- 


35° 


THE    MODERN    CLOCK. 


turn  to  the  same  point  in  relation  to  the  sun.  This  period 
is  called  a  synodic  month.  Its  average  length  is  29  days, 
12  hours,  44  minutes,  2.9  seconds. 

Having  now  understood  these  differences  we  shall  be 
able  to  intelligently  examine  the  various  calendar  mechan- 
isms on  the  market  and  understand  the  reasons  for  their 
apparent  departures  from  regular  mechanical  progression, 
as  the  equation  of  time  gives  us  the  difference  between  real 
and  mean  apparent,  or  solar  time;  we  regulate  our  clocks 
by  means  of  siderial  time;  the  irregular  procession  of  30 
and  31  days  makes  the  civil  calendar  agree  with  the  seasons, 
or  the  tropical  year,  and  the  remainder  of  the  discrepancy 
between  civil  and  siderial  time  is  made  up  in  February  at 
the  period  when  it  is  of  the  least  consequence. 

Simple  Calendar  Work. — Fig.  iii  shows  the  Ameri- 
can method  of  making  a  simple  calendar,  the  example 
shown  being  drawn  from  a  movement  of  the  Waterbury 
Clock  Company  as  a  typical  example.  A'o  attempt  is  made 
here  to  show  the  day  of  the  week  or  the  month.  The  days 
of  the  month  are  shown  by  a  series  of  numbers  from  i  to  31, 
arranged  concentrically  with- the  tim.e  dial  and  the  current 
day  is  indicated  by  a  hand  of  different  color,  carried  on  a 
pipe  outside  the  pipe  of  the  hour  hand  on  the  center  arbor. 

In  order  to  accomplish  this  the  motion  work  for  the 
hands  is  mounted  inside  the  frames,  the  hour  pipe  and 
center  arbor  being  suitably  lengthened.  In  the  Figure  A 
is  the  cannon  pinion ;  B,  the  minute  wheel ;  C,  the 
minute  pinion ;  D,  the  hour  wheel  at  the  rear  end  of 
the  hour  pipe;  this  pipe  projects  through  the  frame  and 
forms  a  bearing  in  the  frame  for  the  center  arbor.  Fric- 
tion-tight on  the  hour  pipe,  in  front  of  the  front  plate,  is 
the  pinion  E,  which  drives  a  wheel  F  of  twice  as  many 
teeth.  This  wheel  F  is  mounted  loosely  on  a  stud  and  has 
a  pin  which  meshes  with  the  teeth  of  a  ratchet  wheel  G.  G 
is  carried  at  the  bottom  end  of  a  pipe  which  fits  loosely  on 


THE    MODIiltX    CLOCK. 


351 


Fig.  111.    Simple  calendar  on  time  train. 


352  THE    MODERN    CLOCK. 

the  hour  pipe  and  carries  the  calendar  hand  H  under  the 
hour  hand  and  close  to  the  dial.  The  pinion  on  the  hour 
pipe  revolves  once  in  twelve  hours.    The  wheel  E  has  twice 


yig.  112.    Calendar  work  for  grandfather  clocks. 

as  many  teeth  and  will  therefore  revolve  once  in  twenty- 
four  hours.  It  moves  the  ratchet  G  one  tooth  at  each  revo- 
lution ;  therefore  the  hand  H  moves  one  space  every  twenty- 
four  hours.  There  arc  31  teeth,  so  that  the  hand  must  be 
set  forward  every  time  it  reaches  the  28th  and  29th  of  Feb- 


THE    MODERN    CLOCK.  353 

ruary  and  the  30th  of  April,  June,  September  and  Novem- 
ber. This  is  the  simplest  and  cheapest  of  all  the  calendars, 
occupies  the  least  space  and  is  frequently  attached  to  nickel 
alarm  clocks  for  that  reason. 

A  simple  calendar  work  often  met  with  in  old  clocks  of 
European  origin  is  shown  in  Fig.  112.  Gearing  with  the 
hour  wheel  is  a  wheel,  A,  having  twice  its  number  of 
teeth,  and  turning  therefore  once  in  twenty-four  hours.  A 
three-armed  lever  is  planted  just  above  this  wheel;  the 
lower  arm  is  slotted  and  the  wheel  carries  a  pin  which 
works  in  this  slot,  so  that  the  lever  vibrates  to  and  fro  once 
every  twenty-four  hours.  The  three  upper  wheels,  B,  C 
and  D  in  the  drawing,  represent  three  star  wheels.  B  has 
seven  teeth,  corresponding  to  the  days  of  the  week;  C  has 
31  teeth,  for  the  days  of  the  month;  and  D  has  12  teeth, 
for  the  months  of  the  year.  Each  carries  a  hand  in  the 
center  of  a  dial  on  the  other  side  of  the  plate.  Every  time 
the  upper  arms  of  the  lever  vibrate  they  move  forward  the 
day  of  the  week,  B,  and  the  day  of  the  month,  C,  wheels 
each  one  tooth.  The  extremities  of  the  two  upper  levers 
are  jointed  so  as  to  yield  on  the  return  vibration,  and  are 
brought  into  position  again  by  a  weak  spring.  There  is  a 
pin  in  the  wheel,  C,  which,  by  pressing  on  a  lever  once 
every  revolution,  actuates  the  month  of  the  year  wheel,  D. 
This  last  lever  is  also  jointed,  and  is  pressed  on  by  a  spring 
so  as  to  return  to  its  original  position.  Each  of  the  star 
wheels  has  a  click  kept  in  contact  by  means  of  a  spring. 
For  months  with  less  than  31  days,  the  day  of  the  month 
hand  has  to  be  shifted  forward. 

Perpetual  Calendar  Work. — Figs.  113,  114,  115,  show 
a  perpetual  calendar  which  gives  the  day  of  the  week,  day 
of  the  month  and  the  month,  making  all  changes  automati- 
cally at  midnight,  and  showing  the  31  days  on  a  dial  be- 
neath the  time  dial,  by  means  of  a  hand,  and  the  days  of 
the  week  and  the  month  by  means  of  cylinders  operating 


■354 


THE    MODERN    CLOCK. 


-O 

A^>K 

IP 1 

'tS^^^^^E-T^^  ^ 

- 

IIP'J    ■ 

r^ 


-jK 


ii:0 


Fig.    113.      Perpetual  Calendar  Movement. 


THE    MODERN    CLOCK.  353 

behind  slots  in  the  dial  on  each  side  of  the  center.  This 
is  also  a  Waterbury  movement.  ' 

A  pinion  on  the  hour  pipe  engages  a  wheel,  A,  having 
twice  the  number  of  teeth  and  mounted  on  an  arbor  which 
projects  through  both  plates.  The  rear  end  of  this  arbor 
carries  a  cam,  B,  on  which  rides  the  end  of  a  lever,  C,  which 
is  pivoted  to  the  rear  frame.  The  lever  is  attached  to  a 
wire,  D,  which  operates  a  sliding  piece,  E,  which  is  weight- 
ed at  its  lower  end.  The  cam,  \yhich,  of  course,  revolves 
once  in  twenty- four  hours,  drops  its  lever  at  midnight  and 
the  weight  on  E  pulls  it  down.  E  bears  a  spring  pawl,  F, 
which  on  its  way  down,  raises  the  spring  actuated  retaining 
click,  H,  and  then  moves  the  31 -toothed  wheel  G  one  notch. 
This  wheel  is  mounted  on  the  arbor  which  carries  the  hand 
and,  of  course,  advances  the  hand. 

Lying  on  top  of  the  wheel,  G,  is  a  cam,  I,  pivoted  to  G 
near  its  circumference  and  having  an  arm  reaching  toward 
the  months  cylinder  and  another  reaching  towards  the  right 
leg  of  the  pawl,  H,  while  it  is  cut  away  in  the  center,  so  as 
to  clear  the  center  arbor  carrying  the  hand.  Trace  this  cam, 
I,  carefully  in  Figs.  113  and  114,  as  its  action  is  vital.  The 
lower  arm  of  this  cam  is  shown  more  clearly  in  Fig.  114. 
It  projects  above  the  wheel  and  engages  the  long  teeth,  J, 
and  the  cam,  K,  mounted  on  the  year  cylinder  arbor; 
where  the  lower  arm  of  I  strikes  one  of  these  teeth  it  shoves 
the  upper  arm  outward,  so  that  it  strikes  the  retaining  end 
of  the  pawl,  H,  and  holds  it  up,  and  the  descending  pawl, 
F,  may  then  push  the  wheel,  G,  forward  for  more  than  one 
tooth.  The  upper  end  of  I  is  broad  enough  to  cover  three 
teeth  of  the  wheel,  G,  when  pushed  outward,  and  the  slot 
in  E  is  long  enough  so  that  F  may  descend  far  enough  to 
push  G  forward  three  teeth  at  once,  unless  it  is  stopped  by 
H  falling  into  a  tooth,  so  that  the  position  of  I,  when  it  is 
holding  up  H  and  the  extra  drop  thus  given  to  E  serve  to 
operate  the  jumps  of  30  to  i,  28  to  i  and  29  to  i  of  the  hand' 
on  the  dial.   The  teeth,  J,  Fig.  1 14,  operate  for  two  notches, 


35^ 


THE    MODERN    CLOCK, 


Fig.  114.    The  months  change  gear. 


THE    MODERN    CLOCK.  ^fi^^ 

thus  making  the. changes  from  30  to  i.  The  wide  tooth,  M, 
and  cam,  K,  acting  together,  make  the  change  for  February 
from  28  to  31.  The  29th  day  is  added  by  the  movement  of 
the  cam,  K,  narrowing  the  acting  surface  once  in  four  years, 
as  follows: 

Looking  at  Fig.  114  we  see  an  ordinary  stop  works  fin- 
ger, mounted  on  the  months  arbor  and  engaging  a  four- 
armed  maltese  cross  on  the  wheel.  Behind  the  wheel  is  a 
circular  cam  (shown  dotted  in)  with  one-fourth  of  its  cir- 
cumference cut  away;  the  pivot  holds  the  cam  and  cross 
rigidly  together  while  permitting  them  to  revolve  loosely  in 
the  wheel.  The  cam,  K,  lies  close  to  the  w^heel  and  is 
pressed  against  the  cam  on  the  cross  by  a  spring,  so  that 
ordinarily  the  full  width  of  M  and  K  act  as  one  piece  on 
the  end  of  the  cam,  I,  which  thus  is  pressed  against  the 
retaining  pawl,  H,  during  the  passage  of  three  teeth,  mak- 
ing the  jump  from  28  to  i  each  of  these  three  years. 

The  fourth  revolution  of  the  maltese  cross  brings  the  cut 
portion  of  its  cam  to  operate  on  K  and  allows  K  to  move 
tehind  M,  thus  narrowing  the  acting  surface  so  that  I  only 
covers  two  teeth  (30  and  31)  for  every  fourth  revolution 
of  the  month's  cylinder,  thus  making  the  leap  year  every 
fourth  year. 

The  months  cylinder  is  kept  in  position  by  the  two-armed 
pawl,  N,  engaging  the  teeth,  L,  which  stand  at  90  degrees 
from  the  wheel,  as  shown  in  Fig.  113.  Attached  to  the 
bearing  for  the  week  cylinder  (not  shown)  is  one  revolu- 
tion of  a  screw  track,  or  worm,  surrounding  the  arbor  for 
the  hand.  Attached  to  the  arbor  is  a  finger,  O,  held  taut 
by  a  spring  and  engaging  the  track,  P.  The  revolution  of 
the  arbor  raises  O  on  P  until  it  slips  off,  when  O,  drawn 
downward  by  its  spring,  raises  the  pawl,  N,  drops  on  one 
of  the  teeth,  L,  and  revolves  the  cylinder  one  notch. 

Q  is  a  shifter  for  raising  the  pawl,  H,  and  allowing  the 
hand  to  be  set. 


358 


THE    MODERN    CLOCK. 


Fig.  115.    The  weeks  chaage  gear. 


THE    MODERN    CLOCK.  3.^^ 

Fig.  115  shows  the  inner  end  of  the  cyHnder  for  the  days 
of  the  week.  There  are  two  sets  of  these  and  fourteen 
teeth  on  the  sprocket,  R,  so  as  to  get  the  two  cyHnders  ap- 
proximately the  same  size  (there  being  14  days  and  12 
months  on  the  respective  cyHnders).  S  is  a  pawl  whose 
upper  end  is  forked  so  as  to  embrace  a  tooth  and  hold  the 
cylinder  in  position.  T  is  a  hook,  carried  on  the  sliding 
piece,  E,  which  swings  outward  in  its  upward  passage  as  E 
is  raised  and  on  its  downward  course  raises  the  pawl,  S, 
and  revolves  the  sprocket,  R,  one  tooth,  thus  changing  the 
day  of  the  week  at  the  same  time  the  hand  is  advanced. 

To  set  the  calendar,  raise  the  pawl,  N,  and  revolve  the 
year  cylinder  until  M  and  K  are  at  their  narrowest  width ; 
that  is,  a  leap  year.  Then  give  the  year  cylinder  as  many 
additional  turns  as  there  are  years  since  the  last  leap  year, 
stopping  on  the  current  month  of  the  current  year.  For 
instance,  if  it  is  two  years  and  four  months  since  the  29th 
of  February  last  occurred,  give  the  cylinder  2  and  4/12 
turns  which  should  bring  you  to  the  current  month,  raise 
the  shifter,  Q,  and  set  the  hand  to  the  current  day.  Then 
raise  the  pawl,  S,  and  set  the  week  cylinder  to  the  current 
day.  Place  the  hour  hand  on  the  movement  so  that  the  cam 
will  drop  E  at  midnight. 

Fig.  116  shows  the  dial  of  Brocot's  calendar  work,  which, 
with  or  without  the  equation  of  time  and  the  lunations,  is 
to  be  met  with  in  many  grandfather,  hall  and  astronomical 
clocks.  We  will  assume  that  all  of  these  features  are  pres- 
ent, in  order  to  completely  cover  the  subject.  It  consists  of 
two  circular  plates  of  which  the  front  plate  is  the  dial  and 
the  rear  plate  carries  the  movement,  arranged  on  both  sides 
of  it.  All  centers  are  therefore  concentric  and  we  have 
marked  them  all  with  the  same  letters  for  better  identifica- 
tion in  the  various  views  as  the  inner  plate  is  turned  about 
to  show  the  reverse  side,  thus  reversing  the  position  of  right 
to  left  in  one  view  of  the  inner  plate. 


360 


THE    MODERN    CLOCK. 


Fig.  117  shows  the  wheel  for  the  phases  of  the  moon, 
which  is  mounted  on  the  outside  of  the  inner  plate  imme- 
diately behind  the  opening  in  the  dial.  The  dark  circles 
h'ave  the  same  color  as  the  sky  of  the  dial  and  the  rest  is 
gilt,  white  or  cream  color  to  show  the  moon  as  in  Fig.  116. 


\  \  i 


^      V    \    ^    '    •    I    '    '    '    /   /       -\ 


y    v<>^e*t^  ^^"'^-^^ 


Fig.  116.    Dial  of  Brocot's  Calendar. 


The  position  of  this  plate  is  also  shown  in  Fig.  120.     By 
the  dotted  circles,  about  the  center  D. 

The  inner  side  containing  the  mechanism  for  indicating 
the  days  of  the  week  and  the  days  of  the  month  is  shown  in 
Fig.  118.  The  calendar  is  actuated  by  means  of  a  pin,  C, 
fixed  to  a  wheel  of  the  movement  which  turns  once  in 
twenty-four  hours  in  the  manner  previously  described  with 


THE    MODEUN    CLOCK.  361 

Fig.  113.  Two  clicks,  G  and  H,  arc  pivoted  to  the  lever, 
M.  G,  by  means  of  its  weighted  end,  see  Fig.  119,  is  kept 
in  contact  with  a  ratchet  wdieel  of  31  teeth,  and  H  with  a 
ratchet  wheel  of  7  teeth.  As  a  part  of  these  clicks  and 
wheels  is  concealed  in  Fig.  118,  they  are  shown  separately 
in  Fig.  119. 

When  the  lever,  AI,  is  moved  to  the  left  as  far  as  it  will 
go  by  the  pin,  e,  the  clicks,  G  and  H,  slip  under  the  teeth ; 
their  beaks  pass  on  to  the  following  tooth ;  when  e  has 
moved  out  of  contact  the  lever,  M,  falls  quickly  by  its  own 
weight,  and  makes  each  click  leap  a  tooth  of  the  respective 
wheels,  B  of  7  and  A  of  31  teeth.  The  arbors  of  these 
wheels  pass  through  the  dial  (Fig.  116),  and  have  each  an 
index  which,  at  every  leap  of  its  own  wheel,  indicates  on  its 
special  dial  the  day  of  the  week  and  the  day  of  the  month. 
A  roll,  or  click,  kept  in  position  by  a  sufficient  spring,  keeps 
each  wheel  in  its  place  during  the  interval  of  time  which 
separates  two  consecutive  leaps. 

This  motion  clearly  provides  for  the  indication  of  the  day 
of  the  week,  and  would  be  also  sufficient  for  the  days  of 
the  month  if  the  index  were  shifted  by  hand  at  the  end  of 
the  short  months. 

To  secure  the  proper  registration  of  the  months  of  30 
days,  for  February  of  28  during  three  years,  and  of  29  in 
leap  year,  we  have  the  following  provision :  The  arbor,  A, 
of  the  day  of  the  month  wheel  goes  through  the  circular 
plate,  and  on  the  other  side  is  fixed  (see  Fig.  120)  a  pinion 
of  10  leaves.  This  pinion,  by  means  of  an  intermediate 
wheel,  I,  works  another  w^heel  (centered  at  C)  of  120 
teeth,  and  consequently  turning  once  in  a  year.  The  arbor 
of  this  last  wheel  bears  an  index  indicating  the  name  of  the 
month,  G,  Fig.  116.  The  arbor,  C,  goes  through  the  plate, 
and  at  the  other  end,  C,  Fig.  118,  is  fixed  a  little  wheel 
gearing  with  a  wheel  having  four  times  as  many  teeth,  and 
which  is  centered  on  a  stud  in  the  plate  at  F.  This  wheel 
is  partly  concealed  in  Fig.  118  by  a  disc  V,  which  is  fixed 


362  THE    MODERN    CLOCK. 

to  it,  and  with  the  wheel  makes  one  turn  in  four  years.  On 
this  disc,  V,  are  made  20  notches,  of  which  the  16  shallow- 
est correspond  to  the  months  of  30  days ;  a  deeper  notch 
corresponds  to  the  month  of  February  of  leap  year,  and  the 
last  three  deepest  to  the  month  of  February  common  years 
in  each  quarternary  period.  The  uncut  portions  of  the  disc 
correspond  to  the  months  of  31  days  in  the  same  period. 
The  wheel.  A,  of  31  teeth,  has  a  pin  (i)  placed  before  the 
tooth  which  corresponds  to  the  28th  of  the  month.  On  the 
lever,  M,  is  pivoted  freely  a  bell-crank  lever  (N),  having  at 


Fig.  117.    Dial  of  Moon's  Phases. 

the  extremity  of  the  lower  arm  a  pin  (o)  which  leans  its 
own  weight  upon  the  edge  of  the  disc,  V,  or  upon  the  bot- 
tom of  one  of  the  notches,  according  to  the  position  of  the 
month,  and  the  upper  arm  of  N  is  therefore  higher  or  lower 
according  to  the  position  of  the  pin,  o,  upon  the  disc. 

It  will  be  easy  to  see  that  when  the  pin,  o,  rests  on  the 
contour  of  the  disc  the  upper  arm,  N,  of  the  bell-crank 
lever  is  as  high  as  possible,  and  out  of  contact  with  the  pin 
as  it  is  dotted  in  the  figure,  and  then  the  31  teeth  of  the 
month  wheel  will  each  leap  successively  one  division  by  the 
action  of  the  click,  G,  as  the  lever,  M,  falls  backward  till 
the  31st  day.  But  when  the  pin,  o,  is  in  one  of  the  shal- 
low notches  of  the  plate,  V,  corresponding  to  the  months  of 
30  days,  the  upper  arm,  N,  of  the  bell-crank  lever  will  take 


THE    MODERN    CLOCK. 


363 


Fig.  118.    Brocot's  Calendar;    Rear  View  of  Calendar  Plate   showing 
Four  Year  Wheel  and  Change  Mechanism, 


364 


THE    MODERN    CLOCK. 


a  lower  position,  and  the  inclination  that  it  will  have  by  the 
forward  movement  of  the  lever,  M,  will  on  the  3Qth  bring 
the  pin,  i,  in  contact  with  the  bottom  of  the  notch,  just  as 
the  lever,  M,  has  accomplished  two-thirds  of  its  forward 
movement,  so  the  last  third  will  be  employed  to  make  the 
wheel  31  advance  one  tooth,  and  the  hand  of  the  dial  by 
consequence  marks  the  31st,  the  quick,  return  of  the  lever, 
M,  as  it  falls  putting  this  hand  to  the  ist  by  the  action  of 
the  click,  G.    If  we  suppose  the  pin,  o,  is  placed  in  the  shal- 


Fig.  119.  Change  Mechanism  behind  the  Four  Year  Wheel  in  Fig.  118 


lowest  of  the  four  deep  notches,  that  one  for  February  of 
leap  year,  the  upper  end  of  the  arm,  N,  will  take  a  position 
lower  still,  and  on  the  29th  the  pin,  i,  will  be  met  by  the 
bottom  of  the  notch,  just  as  the  lever  has  made  one-third  of 
its  forward  course,  so  the  other  two-thirds  of  the  forward 
movement  will  serve  to  make  two  teeth  of  the  wheel  of  31 
jump.  Then  the  hand  of  the  dial,  A,  Figs.  116  and  118, 
will  indicate  31,  and  the  ordinary  quick  return  of  the  lever, 
M,  with  its  detent,  G,  will  put  it  to  the  1st.  Lastly,  if,  as 
it  is  represented  in  the  figure,  the  pin,  o,  is  in  one  of  the 
three  deepest  notches,  corresponding  to  the  months  of  Feb- 
ruary in  ordinary  years,  the  pin  will  be  in  the  bottom  of 


THE    MODERN    CLOCK.  365 

the  notch  on  the  28th  just  at  the  moment  the  lever  begins 
its  movement,  and  three  teeth  will  pass  before  the  return 
of  the  lever  makes  the  hand  leap  from  the  31st  to  the  ist. 

The  pin,  0,  easily  gets  out  of  the  shallow  notches,  which, 
as  will  be  seen,  are  sloped  away  to  facilitate  its  doing  so. 
To  help  it  out  of  the  deeper  notches  there  is  a  weighted 
finger  (j)  on  the  arbor  of  the  annual  wheel.  This  finger, 
having  an  angular  movement  much  larger  than  the  one  of 
the  disc,  V,  puts  the  pin,  o,  out  of  the  notch  before  the  notch 
has  sensibly  changed  its  position. 

Phases  of  the  Moon. — The  phases  of  the  moon  are  ob- 
tained by  a  pinion  of  10,  Fig.  120,  on  the  arbor,  B,  which 
gears  with  the  wheel  of  84  teeth,  fixed  on  another  of  75, 
Avhich  last  gears  with  a  wheel  of  113,  making  one  revolu- 
tion in  three  lunations.  By  this  means  there  is  an  error 
only  of  .00008  day  per  lunation.  On  the  wheel  of  113  is 
fixed  a  plate  on  which  are  three  discs  colored  blue,  having 
between  them  a  distance  equal  to  their  diameter,  as  shown, 
in  Fig.  117,  these  discs  slipping  under  a  circular  aperture 
made  in  the  dial,  produce  the  successive  appearance  of  the 
phases  of  the  moon. 

Equation  of  Time. — On  the  arbor  of  the  annual  wheel, 
C,  Figs.  116,  118,  120,  is  fixed  a  brass  cam,  Y,  on  the  edge 
of  which  leans  the  pin,  s,  fixed  to  a  circular  rack,  R.  This 
rack  gears  with  the  central  wheel,  K,  which  carries  the 
hand  for  the  equation.  That  hand  faces  XII  the  15th  of 
April,  14th  of  June,  ist  of  September  and  the  25th  of  De- 
cember. At  those  dates  the  pin,  s,  is  in  the  position  of  the 
four  dots  marked  on  the  cam,  Y.  The  shape  of  the  cam, 
Y,  must  be  such  as  will  lead  the  hand  to  indicate  the  dif- 
ference between  solar  and  mean  time,  as  given  in  the  table 
of  the  Nautical  almanac. 

To  set  the  calendar  first  see  that  the  return  of  the  lever, 
M,  be  made  at  the  moment  of  midnight.  To  adjust  the 
hand  of  the  days  of  the  week,  B,  look  at  an  almanac  and 


366 


THE    MODERN    CLOCK. 


see  what  day  before  the  actual  date  there  was  a  full  or  new 
moon.  If  it  was  new  moon  on  Thursday,  it  would  be  nec- 
essary, by  means  of  a  small  button  fixed  at  the  back,  on  the 
arbor  of  the  hand  of  the  wheel,  B,  of  the  week,  to  make  as 
many  returns  as  requisite  to  obtain  a  new  moon,  this  hand 


S'/T 


s-m^- 


Fig.  120.  Brocot's  Calender:  "Wheels  and  Pinions  under  the  Dial  with 
their  Number  of  Teeth. 


pointing. to  a  Thursday;  afterward  bring  back  the  hand  to 
the  actual  date,  passing  the  number  of  divisions  correspond- 
ing to  the  days  elapsed  since  the  new  moon.  To  adjust  the 
hand  of  the  day  of  the  month,  A,  see  if  the  pin,  o,  is  in  the 
proper  notch.  If  for  the  leap  year,  it  is  in  the  month  of 
February  in  the  shallowest  of  the  four  deep  notches  (o)  ; 
if  for  the  same  month  of  the  first  year  after  leap  year,  then 
the  pin  should  be,  of  course,  in  the  notch,  i,  and  so  on. 


CHAPTER  XX. 

HAMMERS,    GONGS    AND   BELLS. 

Just  as  the  tone  of  a  piano  depends  very  largely  upon  the 
condition  of  the  felts  on  the  hammers  which  strike  the 
wires,  so  does  the  tone  of  a  clock  gong  or  bell  depend  on 
its  hammer  action.  The  deep,  soft,  resonant  tone  in  either 
instance  depends  on  the  vibration  being  produced  by  some- 
thing softer  than  metal.  Ordinarily  this  condition  is  reached 
by  facing  the  hammer  with  leather.  The  second  essential 
is  that  the  hammer  shall  immediately  rebound,  clear  of  the 
bell,  so  as  not  to  interfere  with  the  vibrations  it  has  set  up 
in  the  bell,  wire  or  tube.  As  the  leather  gets  harder  the 
tone  becomes  harsher  and  ''tinny,"  sometimes  changing  to 
another  much  higher  tone  and  entirely  destroying  the 
harmony.  The  remedy  is  either  to  oil  the  leather  on  the 
hammers,  or  if  they  are  much  worn  to  substitute  new  and 
thicker  leathers  until  the  tone  is  sufficiently  mellowed,  so 
that  a  vigorous  blow  will  still  produce  a  mellow  tone  of 
sufficient  carrying  power.  A  piece  of  round  leather  belting 
will  be  found  very  convenient  for  this  purpose. 

The  superiority  of  a  chiming  clock  lies  in  its  hammer 
action.  If  this  mechanism  is  not  perfect,  only  inferior  re- 
sults can  be  obtained.  The  perfect  hammer  is  the  one  that 
acts  with  the  smallest  strain  and  is  operated  with  the  least 
power.  Heavy  weights  create  a  tremendous  strain  on  the 
mechanism  and  bring  disastrous  results  when  one  of  the 
suspending  cords  break.  The  method  of  lifting  the  ham- 
mer is  one  of  importance,  and  the  action  of  the  hammer 
spring  is  but  seldom  right  on  old  clocks  brought  in  for  re- 
pairs, especially  if  it  be  a  spring  bent  oyer  to  a  right  angle 

367 


368  THE    MODERN    CI.OCK. 

at  its  point.  If  there  are  two  springs,  one  to  force  the  ham- 
mer down  after  the  clock  has  raised  it  up,  and  another 
shorter  one,  fastened  on  to  the  pillar,  tO'  act  as  a  counter- 
spring  and  prevent  the  hammer  from  jarring  on  the  bell, 
there  will  seldom  be  any  difficulty  in  repairing  it;  and  the 
only  operation  necessary  to  be  done  is  to  file  worn  parts, 
polish  the  acting  parts,  set  the  springs  a  little  stronger,  and 
the  thing  is  done.  But  if  there  is  only  one  spring  some 
further  attention  will  be  necessary,  because  the  action  of  the 
one  spring  answers  the  purpose  of  the  two  previously  men- 
tioned, and  to  arrange  it  so  that  the  hammer  will  be  lifted 
with  the  greatest  ease  and  then  strike  on  the  bell  with  the 
greatest  force,  and  without  jarring,  requires  some  experi- 
ence. That  part  of  the  hammer-stem  which  the  spring  acts 
on  should  never  be  filed  or  bent  beyond  the  center  of  the 
arbor,  as  is  sometimes  done,  because  in  such  a  case  the  ham- 
mer-spring has  a  sliding  motion  when  it  is  in  action,  and 
some  of  the  force  of  the  spring  is  thereby  lost.  The  point 
of  the  spring  should  also  be  made  to  work  as  near  to  the 
center  of  the  arbor  as  it  is  possible  to  get  it,  and  the  flat 
end  of  the  spring  should  be  at  a  right  angle  with  the  edge 
of  the  frame,  and  that  part  of  the  hammer-stem  that  strikes 
against  the  flat  end  of  the  spring  should  be  formed  with  a 
curve  that  will  stop  the  hammer  in  a  particular  position  and 
prevent  it  jarring  on  the  bell.  This  curve  can  only  be  deter- 
mined by  experience ;  but  a  curve  equal  to  a  circle  six  inches 
in  diameter  will  be  nearly  right. 

The  action  of  the  pin  wheel  on  the  hammer-tail  is  also 
of  importance.  The  acting  face  of  the  hammer-tail  should 
be  in  a  line  with  the  center  of  the  pin-wheel,  or  a  very  little 
above  it,  but  never  below  it,  for  then  it  becomes  more  dif- 
ficult for  the  clock  to  lift  the  hammer,  and  the  hammer- 
tail  should  be  of  such  a  length  as  to  drop  from  the  pins  of 
the  pin-wheel,  and  when  it  stops  be  about  the  distance  of 
two  teeth  of  the  wheel  from  the  next  pin.  This  allows  the 
wheel- work  to  gain  a  little  force  before  lifting  the  hammer, 


THE    MODERN    CLOCK.  369 

which  is  sometimes  desirable  when  the  clock  is  a  little  dirty 
or  nearly  run  down.  We  might  also  mention  that  in  set- 
ting the  hammer-spring  to  work  with  greater  force  it"  is 
always  well  to  try  and  stop  the  fly  with  your  finger  when 
the  clock  is  striking,  and  if  this  can  be  done  it  indicates 
that  the  hammer  spring  is  stronger  than  the  striking  power 
of  the  clock  can  bear,  and  it  ought  to  be  weakened,  because 
the  striking  part  will  be  sure  to  stop  whenever  the  clock 
gets  the  least  dirty. 

Gong  wires  are  also  the  cause  of  faulty  tones.  In  the 
factories  these  are  made  by  coiling  wires  of  suitable  lengths 
and  sections  on  arbors  in  a  lathe.  They  are  then  heated  to 
a  dull  red  and  hardened  by  dipping  in  water  or  oil.  After 
cooling  they  are  trued  in  the  round  and  the  flat  like  a  watch 
hairspring  and  then  drawn  to  a  blue  temper.  The  tone 
comes  with  the  tempering,  and  if  they  are  afterwards  bent 
beyond  the  point  where  they  will  spring  back  to  shape  the 
tone  is  interfered  with.  Many  repairers,  not  being  aware 
of  this  fact,  have  ruined  the  tone  of  a  gong  wire  while  try- 
ing to  true  it  up  by  bending  with  pliers.  When  the  owner 
is  particular  about  the  tone  of  the  clock,  a  new  gong  should 
always  be  put  in  if  the  old  one  is  badly  bent. 

The  wires  are  soldered  to  their  centers  and  if  they  are 
at  all  loose  they  should  be  refastened  in  the  same  manner 
if  it  can  be  done  without  drawing  the  temper  of  the  wire. 
When  this  cannot  be  done  a  plug  of  solder  may  be  driven 
in  between  the  wire  and  the  side  of  the  hole  so  as  to  stop 
all  vibration  or  the  solder  already  in  place  may  be  driven 
down  so  as  to  make  all  tight,  as  any  vibration  at  this  point 
will  interfere  with  the  tone. 

Tuning  the  Bells. — Bells  only  vefy  slightly  out  of 
tone  offend  the  musical  ear,  and  they  may  easily  be  correct- 
ed to  the  extent  of  half  a  tone.  To  sharpen  the  tone  make 
the  bell  shorter  by  turning  away  the  edge  of  it  if  it  be  a 
shell,  or  by  cutting  off  if  it  be  a  rod  or  tube ;  to  flatten  the 


370 


THE    MODERN    CLOCK. 


-T1C10D 


^. 


%i 


it 


3; 


^ 


2c 


i=iE 


5E 


■rJ 


yi 


>1 


Fig.  121.    The  pins  in  the  chiming  barrels. 


THE    MODERN    CLOCK.  37t 

tone,  thin  the  back  basin-shaped  part  of  the  bell  by  turn- 
ing some  off  the  outside.  Bells  which  are  cracked  give  a 
poor  sound  because  the  edges  of  the  crack  interfere  with 
each  other  when  vibrating.  They  may  be  repaired  by  saw- 
ing through  the  crack  to  the  end  of  it,  so  that  the  edges  will 
not  touch  each  other  when  vibrating.  If  there  is  danger  of 
the  crack  extending  further  into  the  bell,  first  drill  a  round 
hole  in  the  soHd  metal  just  beyond  the  end  of  the  crack, 
and  then  saw  through  into  the  hole ;  this  will  generally  pre- 
vent any  further  trouble. 

Marking  the  Chime  Barrel. — The  chime  barrel  in 
small  clocks  is  of  brass  and  should  be  as  large  in  diameter 
as  "can  be  conveniently  got  in.  To  mark  off  the  positions  of 
the  pins  for  the  Cambridge  chimes,  first  put  the  barrel  in 
the  lathe  and  trace  circles  round  the  barrel  at  distances 
apart  corresponding  to  the  positions  of  the  hammer  tails. 
There  are  five  chimes  of  four  bells  each  for  every  rotation 
of  the  barrel,  and  a  rest  equal  to  two  or  three  notes  be- 
tween each  chime.  Assuming  the  rest  to  be  equal  to  three 
notes,  divide  the  circumference  of  the  barrel  into  thirty- 
five  equal  parts  by  means  of  an  index  plate,  and  draw  lines 
at  these  points  across  the  barrel  with  the  point  of  the  tool 
bv  moving  it  with  the  slide  rest  screw.  Call  the  hammer 
for  the  highest  note  D,  and  that  for  the  lowest  note  F. 
Then  the  first  pin  is  to  be  inserted  where  one  of  the  lines 
across  the  barrel  crosses  the  first  circle;  the  second  pin 
where  the  next  line  crosses  the  second  circle;  the  third  pin 
where  the  third  line  crosses  the  third  circle  and  the  fourth 
pin  where  the  fourth  line  crosses  the  four  circle,  because 
the  notes  of  the  first  chime  are  in  the  order,  D,  C,  Bb,  F. 
Then  miss  three  lines  for  the  rest.  The  first  note  of  the 
second  chime  is  Bb  and  the  pins  for  it  will  consequently  be 
inserted  where  the  first  line  after  the  rest  crosses  the  third 
circle,  and  so  on.  Where  two  or  more  notes  on  the  same 
bell  come  so  close  as  to  make  it  difficult  to  strike  them  prop- 


372 


THE    MODERN    CLOCK. 


erly,  it  is  usual  to  put  in  another  hammer,  as  it  shown  in 
Fig.  121,  where  there  are  two  Fs.  In  fine  clocks  the  pins 
are  of  varying  lengths  so  as  to  strike  the  hammers  on  the 
bells  with  varying  force  and  thus  give  more  expression  to 
the  music. 

The  following  gives  the  Cambridge  Chimes,  which  are 
used  in  the  Westminster  Great  Clock.  They  are  founded 
on  a  phrase  in  the  opening  symphony  of  Handel's  air,  'T 


1st 
Quarter 

2nd  . 
Quarter. 

3rd 
Quarter. 


^ 


^ 


^s 


t 


i 


^ 


^ 


3te 


22: 


■f^^^M^gJfFF?^! 


Hour. 


i 


&i 


m^- 


i3t 


^^^ 


$ 


t 


^^ 


22: 


H^M 


Fig.  122.    Westminster  chimes. 


know  that  my  Redeemer  liveth,"  and  were  arranged  by  Dr. 
Crotch  for  the  clock  of  Great  St.  Mary's,  Cambridge,  in 
1793- 

In  Europe  these  chiming  clocks  are  sometimes  very  elab- 
orate, as  the  following  description  of  a  set  of  bells  in  Bel- 
gium will  show: 

"So  far  as  the  experience  of  the  writer  goes  the  Belgian 
carillons  are  invariably  constructed  on  one  prevailing  plan, 
with  the  exception  that  the  metal  used  for  the  cylinder  is 
generally  brass;  here,  however,  it  is  of  steel,  and  consists 
of  a  large  barrel  measuring  4  feet  2  inches  in  width  and  3 


THE    MODERN    CLOCK.  373 

feet  6  inches  in  diameter,  its  surface  being  pierced  with 
horizontal  lines  of  small  square  holes  about  ^  inch  square. 
There  are  lines  of  60  of  these  in  the  width  of  the  barrel, 
while  there  are  120  lines  of  them  round  the  circumference, 
making  a  total  of  7,200  holes.  The  drilling  of  these,  of 
course,  takes  place  when  the  cylinder  is  made,  and,  so  far 
as  this  part  is  concerned,  the  barrel  is  complete  before  it  is 
brought  to  the  tower. 

"Into  these  square  holes  are  fixed  the  'pins,'  adjusted  on 
the  inside  of  the  cylinder  by  nuts. 

"The  pins  are  of  steel  of  finely  graduated  sizes,  corres- 
ponding with  the  value  of  the  notes  of  music.  Some  idea 
of  the  precision  obtainable  may  be  gathered  by  the  fact,  as 
the  carillonneur  told  the  writer,  that  there  were  no  less 
than  24  grades  of  pins,  so  as  to  insure  the  greatest  accuracy 
of  striking  the  bells. 

"Over  the  cylinder  are  60  steel  levers  with  steel  nibs; 
these  are  lifted  by  the  'pins'  and,  connected  by  wires  with 
the  hammers,  strike  the  bells. 

"The  35  bells  are  furnished  with  J2  hammers,  which  are 
fixed  as  ordinary  clock-hammers  outside  of  the  bells;  three 
of  the  bells  (in  the  ring  of  eight)  have  a  single  hammer 
only,  the  limited  space  in  the  'cage'  making  it  impossible 
to  put  more,  while  others  are  supplied  with  two  or  three 
apiece  for  use  in  rapidly  repeating  notes  of  the  music.  On 
a  visit  some  years  ago  to  the  carillon  at  Malines,  the  writer 
noticed  that  some  of  the  bells  there  had  no  less  than  five 
hammers  apiece. 

"Obviously,  though  there  are  'J2  hammers  in  connection 
with  the  carillon,  only  60,  corresponding  with  the  number 
of  levers,  can  be  used  at  one  time;  these  are  selected  ac- 
cording to  the  requirement  of  the  tune;  in  case  of  new 
tunes,  the  wires  can  easily  be  adjusted  so  as  to  bring  other 
hammers  and  bells  into  use. 

"The  feature  of  the  Belgian  carillons  is  that  instead  of 
the  single  notes  of  the  air  being  struck  as  with  the  old 


374  '^^^E    MODERN    CLOCK. 

familiar  'chimes/  harmonized  tunes  of  great  intricacy  are 
rendered  with  chords  of  three,  four  or  even  five  bells  strik- 
ing at  one  time. 

"The  cylinder  here  is  capable  of  120  'measures'  of  music, 
but^as  „ a  matter  of  fact  it  is  subdivided  so  that  half  a  revo- 
lution plays  every  hour. 

"A  march  is,  as  a  rule,  played  at  the  odd  hours,  and  the 
national  air  at  the  even,  but  the  bells  are  silent  after  9  p.  m. 
and  start  again  at  8  a.  m. 

"The  motive  power  is  supplied  by  a  weight  of  8  cwt., 
and  is  controlled  by  a  powerful  fly  of  four  fans  artistically 
formed  to  represent  swans.  It  may  be  mentioned  that  the 
keyboard  for  hand-playing  consists  of  thirty-five  keys  of 
wood  and  eleven  pedals;  these,  as  indeed  the  whole  appa- 
rartus  of  this  part,  are  entirely  separate  from  the  automatic 
carillon ;  in  this  instance  the  keys  connect  with  the  clappers 
of  the  bells  and  have  no  association  with  the  hammers. 
The  pedals  are  connected  with  the  eleven  largest  bells  and 
are  supplementary  to  the  hour  key." 

Tubular  Chimes  are  tubes  of  bell  metal,  cut  to  the 
proper  lengths  to  secure  the  desired  tones  and  generally, 
but  not  always,  nickel  plated.  As  they  take  up  much  room 
in  the  clock,  they  are  generally  suspended  from  hooks  at 
the  top  of  the  back  board  of  the  case,  being  attached  to  the 
hooks  by  loops  of  silk  or  gut  cords,  passed  through  holes 
drilled  in  the  wall  of  the  tubes  near  the  top  ends.  The  hour 
tube,  being  long  and  large,  generally  extends  nearly  to 
the  bottom  of  a  six-foot  case,  while  the  others  range  up- 
wards, shortening  according  to  the  increase  of  pitch  of  the 
notes  which  they  represent. 

This  makes  it  necessary  to  place  the  movement  on  a  seat 
board  and  hang  the  pendulum  from  the  front  plate  of  the 
movement,  so  that  such  clocks  have,  as  a  rule,  comparative- 
ly light  pendulums.  On  account  of  the  position  and  the 
great  spread  of  the  tubes,  the  chiming  cylinder  and  ham- 
mers  are  placed  on  top  of  the  movement,  parallel  with  the 


TIIF    MODERN    CLOCK.  375 

plates,  and  operated  from  the  striking  train  by  means  of 
bevel  gears  or  a  contrate  wheel.  The  hammers  are  placed 
vertically  on  spring  hammer  stalks  and  connected  with  the 
chiming  cylinder  levers  by  silken  cords.  This  gives  great 
freedom  of  hammer  action  and  results  in  very  perfect  tones. 
The  hammers  must  of  course  be  each  opposite  its  own 
tube  and  thus  they  are  rather  far  apart,  which  necessitates 
a  long  cylinder.  This  gives  room  for  several  sets  of 
chimes  on  the  same  cylinder  if  desired,  as  a  very  slip^ht 
horizontal  movement  of  the  cylinder  would  move  the  pins 
out  of  action  with  the  levers  and  bring  another  set  into 
action  or  cause  the  chimes  to  remain  silent. 

Practically  all  of  the  manufacturers  of  "hall"  or  chim- 
ing clocks  import  the  movements  and  supply  American 
cases,  hammers  and  bells.  The  reason  is  that  there  is  so 
little  sale  for  them  (from  a  factory  standpoint)  that  one 
factory  could  supply  the  world  with  movements  for  this 
class  of  clocks  without  working  overtime,  and  therefore  it 
would  be  useless  to  make  up  the  tools  for  them  when  they 
can  be  bought  without  incurring  that  expense. 


CHAPTER  XXL 

ELECTRIC  CLOCKS  AND  BATTERIES. 

Electric  clocks  may  be  divided  into  three  kinds,  or  prin- 
cipal divisions.  Of  the  first  class  are  those  in  which  the 
pendulum  is  driven  directly  from  the  armature  by  electric 
impulse,  or  by  means  of  a  weight  dropping  on  an  arm  pro- 
jecting from  the  pendulum.  In  this  case  the  entire  train  of 
the  clock  consists  of  a  ratchet  wheel  and  the  dial  work. 

The  second  class  comprises  the  regular  train  from  the 
center  to  the  arbor.  This  class  has  a  spring  on  the  center 
arbor,  wound  more  or  less  frequently  by  electricity.  In 
this  case  the  aim  is  to  keep  the  spring  constantly  wound,  so 
that  the  tension  is  almost  as  evenly  divided  as  with  the 
ordinary  weight  clock,  such  as  is  used  in  jewelers'  regu- 
lators. 

The  third  system  uses  a  weight  on  the  end  of  a  lever 
connected  with  a  ratchet  wheel  on  the  center  arbor  and . 
does  away  with  springs.     One  type  of  each  of  these  clocks 
will  be  described  so  that  jewelers  may  comprehend  the  prin- 
ciples on  which  the  three  types  are  built 

In  the  Gillette  Electro-Automatic,  which  belongs  to  the 
class  first  mentioned,  the  ordinary  clock  principle  is  re- 
versed. Instead  of  the  works  driving  the  pendulum,  the 
pendulum  drives  the  train,  through  the  medium  of  a  pawl 
and  ratchet  mechanism  on  the  center  arbor.  The  pendu- 
lum is  kept  swinging  by  means  of  an  impulse  given  every 
tenth  beat  by  an  electro-magnet.  This  impulse  is  caused 
by  the  weight  of  the  armature  as  it  falls  away  from  the 
magnet  ends,  the  current  being  used  solely  to  pull  back  and 
re-set  the  armature  for  the  next  impulse.  Any  variation  in 
the  current,  therefore,  does  not  affect  the  regulation  of  the 

376 


THE    MODERN    CLOCK 


377 


Fig.  123.    Gillette  Clock  (Pendulum  Driven) 


378  THE    MODERN    CLOCK. 

clock,  as  the  power  is  obtained  from  gravity  only,  by 
means  of  the  falling  weight.  Referring  to  the  drawings. 
Figs.  123  and  124,  it  is  seen  that  each  time  the  pendulum 
swings  the  train  is  pushed  one  tooth  forward.  A  cam  is 
carried  by  the  ratchet  (center)  arbor  in  which  a  slot  is  pro- 
vided at  a  position  equivalent  to  every  fifth  tooth  of  the 
ratchet.  Into  this  slot  drops  the  end  of  a, lever,  releasing  at 
its  other  end  the  armature  prop.  Thus  at  the  next  beat  of 
the  pendulum  the  armature  is  released  and  in  its  downward 
swing  impulses  the  pendulum,  giving  it  sufficient  mo- 
mentum to  carry  it  over  the  succeeding  five  swings. 

The  action  of  the  life-giving  armature  is  entirely  discon- 
nected and  independent  of  the  clock  mechanism.  It  acts 
on  its  own  accord  when  released  every  tenth  beat  and  auto- 
matically gives  its  impulse  and  re-sets  itself.  It  is  pro- 
vided with  a  double-acting  contact  spring  (see  Fig.  125) 
which  "flips"  a  contact  leaf  from  one  adjustable  contact 
screw  to  the  other  as  the  action  of  the  armature  causes  the 
spring  to  pass  over  its  dead  center.  Thus,  when  the  arma- 
ture reaches  the  lowest  point  in  its  drop  (Figs.  126  and 
127)  the  leaf  snaps  against  the  right  contact  screw,  the  cir- 
cuit is  completed,  the  magnet  energized  and  the  armature 
drawn  up.  As  the  armature  rises  above  a  certain  point,  the 
dead  center  of  the  flipper  spring  is  again  crossed  and  the 
leaf  snaps  back  against  the  post  at  the  left.  In  the  mean- 
time, however,  the  armature  prop  has  slipped  under  the  end 
of  the  armature  and  retains  it  until  the  time  comes  for  the 
next  impulse. 

In  adjusting  the  mechanism  of  this  type  of  clock  the  in- 
creasing pendulum  swing  should  catch  and  push  the  ratchet 
before  the  buffer  strikes  and  lifts  the  armature  from  the 
prop.  The  adjustment  of  the  "flipper"  contact  screws 
(with  1-32  inch  play)  should  be  such  that  as  the  armature 
falls  the  contact  leaf  will  be  thrown  and  the  armature 
drawn  up  at  a  p9int  just  beyond  the  half-way  position  in 
the  swing  of  the  pendulum.    The  power  of  the  impulse  can 


THE    MODERN    CLOCK. 


379 


Fig.  124.    Side  View. 


3S0  THE    MODERN    CLOCK. 

be  regulated  by  turning  the  adjusting  post  with  pHers,  thus 
varying  the  tension  of  the  armature  spring,  the  pull  of 
which  reinforces  the  weight  of  the  armature.  •  Care  should 
be  taken,  however,  that  the  tension  is  not  beyond  the  "quick 
action"  power  of  the  electro-magnet.  It  is  much  better  to 
ease  up  the  movement  in  other  ways  before  putting  too 
great  a  load  on  the  life  of  the  battery. 

The  electrical  contacts  on  the  leaf  and  screw  are  platinum 
tipped  to  prevent  burning  by  the  electric  sparking  at  the 
''make"  and  ''break."  This  sparking  is  also  much  reduced 
by  means  of  a  resistance  coil  placed  in  series  connection 
with  the  magnet  coil,  Fig.  127,  to  reduce  the  amount  of 
current  used.  If  this  coil  is  removed  or  disconnected  the 
constant  sparking  and  heat  would  soon  burn  out  the  con- 
tact tips. 

Care  should  be  taken  to  see  that  the  batteries  are  dated 
and  the  battery  connections  are  clean  at  the  time  of  sliding 
in  a  new  battery.  The  brush  which  makes  connection  with 
the  center  or  carbon  post  of  the  battery  is  insulated  with 
mica  from  the  framework  of  the  case.  The  other  connec- 
tion is  made  from  the  contact  of  the  uncovered  zinc  case  of 
the  battery  with  the  metal  clock  case  surrounding  it.  The 
contact  points  should  be  bright  and  smooth  to  insure  good 
contacts. 

These  clocks  need  but  little  cleaning  of  the  works  as  no 
oil  whatever  is  used,  except  at  one  place,  viz.,  the  armature 
pivot.  Oil  should  never  be  used  on  the  train  bearings,  or 
other  parts.  This  clock  ran  successfully  on  the  elevated 
railway  platforms  of  the  loop  in  Chicago  where  no  other 
pendulum  clock  could  be  operated  on  account  of  the  con- 
stant shaking. 

In  considering  the  electrical  systems  of  these  clocks,  let 
us  commence  with  the  batteries.  While  undoubtedly  great 
improvements  have  been  made  in  the  present  form  of  dry 
battery  they  are  still  very  far  from  giving  entire  satisfac- 
tion.    Practically  all   of  them  are  of  one  kind,  which  is 


THE    MODERN    CLOCK. 


3£' 


that  which  produces  electricity  at  i^^  volts  from  zinc,  car- 
bon and  sal-ammoniac,  with  a  depolarizer  added  to  the 
elements  to  absorb  the  hydrogen.  The  chemical  action  of 
such  a  battery  is  as  follows: 


/ 


Fig.  125. 

The  water  in  the  electrolite  comes  in  contact  with  the  zinc 
and  is  decomposed  thereby,  the  oxygen  being  taken  from 
the  water  by  the  zinc,  forming  oxide  of  zinc  and  leaving 
the  hydrogen  in  the  form  of  minute  bubbles  attached  to 
the  zinc.  As  this,  if  allowed  to  stand,  would  shut  off  the 
water  from  reaching  the  zinc,  chemical  action  would  there- 
fore soon  cease  and  when  this  happens  the  battery  is  said 
to  be  polarized  and  no  current  can  be  had  from  it. 


THE    MODERN    CLOCK. 


THE    MODERN    CLOCK.  383 

In  order  to  take  care  of  the  hydrogen  and  thus  insure  the 
constant  action  of  the  battery,  oxide  of  manganese  is  added 
to  the  contents  of  the  cell,  generally  as  a  mixture  with  the 
carbon  element.  Manganese  has  the  property  of  absorbing 
oxygen  very  rapidly  and  of  giving  it  off  quite  easily.  There- 
fore while  the  hydrogen  is  being  formed  on  the  zinc,  it  be- 
comes an  easy  matter  for  it  to  leave  the  zinc  and  take  its 
proper  quantity  of  oxygen  from  the  manganese  and  again 
form  water,  which  is  again  decomposed  by  the  zinc.  As 
long  as  this  cycle  of  chemical  action  takes  place  the  battery 
will  continue  to  give  good  satisfaction,  and  usually  when  a 
battery  gives  out  it  is  because  the  depolarizer  is  exhausted, 
for  the  reason  that  the  carbon  is  not  affected  at  all  and  the 
zinc  element  forming  the  container  is  present  in  sufficient 
quantity  to  outlast  the  chemical  action  of  the  total  mass. 

There  are  great  differences  in  the  various  makes  of  bat- 
teries ;  also  in  the  methods  of  their  construction.  It  would 
seem  to  be  an  easy  matter  for  a  chemist  to  figure  out 
exactly  how  much  depolarizer  would  serve  the  purpose 
for  a  given  quantity  of  zinc  and  carbon  and  therefore  to 
make  a  battery  which  should  give  an  exact  performance 
that  could  be  anticipated.  In  reality,  however,  this  is  not 
the  case,  owing  to  the  various  conditions.  There  are  three 
qualities  of  manganese  in  the  market ;  the  Japanese,  which 
is  the  best  and  most  costly ;  the  German,  which  comes  sec- 
ond, and  the  American,  which  is  the  cheapest  and  varies  in 
quality  so  much  as  to  be  more  or  less  a  matter  of  guess- 
work. We  must  remember  that  in  making  batteries  for  the 
price  at  which  they  are  now  sold  on  the  market  we  are 
obliged  to  take  mxaterials  in  commercial  quantities  and 
commercial  qualities  and  cannot  depend  upon  the  chemically 
pure  materials  with  which  the  chemists'  tlieories  are  always 
formulated.  This  therefore  introduces  several  elements  of 
uncertainty. 

In  practice  the  Japanese  manganese  will  stand  up  for  a 
far  longer  time  than  any  other  that  is  known  and  it  is 


384  THE    MODERN    CLOCK. 

used  in  all  special  batteries  where  quality  and  length  of  life 
are  considered  of  more  importance  than  the  price.  The 
German  manganese  comes  next.  Then  comes  a  mixture  of 
American  and  German  manganese,  and  finally  the  Ameri- 
can  manganese,  which  is  used  in  making  the  cheaper  bat- 
teries which  are  sorted  afterwards,  as  we  shall  explain 
farther  on.  These  batteries  are  sealed  after  having  been 
made  in  large  quantities,  say  five  thousand  or  ten  thousand 
in  the  lot,  and  kept  for  thirty  days,  after  which  they  are 
tested.  The  batteries  which  are  likely  to  give  short-life  will 
show  a  local  action  and  consequent  reduction  of  output  in 
thirty  days.  They  are,  therefore,  sorted  out,  much  as  eggs 
are  candled  on  being  received  in  a  storage  warehouse,  for 
the  reason  that  after  a  cell  has  been  made  and  put  together 
it  would  cost  more  to  find  out  what  was  the  matter  with  it 
and  remedy  that  than  it  would  to  make  a  new  cell.  Many 
of  the  battery  manufacturers,  therefore,  make  up  their  bat- 
teries with  an  attempt  to  reach  the  highest  standard.  They 
are  sorted  for  grade  in  thirty  days  and  those  which  have 
attained  the  point  desired  are  labeled  as  the  factories'  best 
battery  and  are  sold  at  the  highest  prices.  The  others  have 
been  graded  down  exclusively  and  labeled  differently  until 
those  which  are  positively  known  to  be  short-lived  arc  run 
out  and  disposed  of  as  the  factories'  cheapest  product  under 
still  another  label. 

When  buying  batteries  always  look  to  see  that  the  tops 
are  not  cracked,  as  if  the  seal  on  the  cell  is  broken,  chem- 
ical action  induced  from  contact  with  the  air  as  the  battery 
dries  out,  will  rapidly  deteriorate  the  depolarizer  and  sul- 
phate the  zinc,  both  of  which  are  of  course  a  constant  draft 
on  the  life  of  the  battery,  which  contains  only  a  stated 
quantity  of  energy  in  the  beginning.  Always  examine  the 
terminal  connections  to  see  that  they  are  tight  and  solid. 

Batteries  when  made  up  are  always  dated  by  the  factory, 
but  this  does  the  purchaser  little  good,  as  the  dates  are  in 
codes  of  letters,  figures,  or  letters  and  figures,  and  are  coi?,- 


THE    MODERN    CLOCK.  385 

stantly  chang'ed  so  that  even  the  dealers  who  are  handling 
thousands  of  them  are  unable  to  read  the  code.  This  is 
done  because  many  people  are  prone  to  blame  the  battery 
for  other  defects  in  the  electrical  system  and  many  who  are 
using  great  quantities  would  find  an  incentive  to  switch  the 
covers  on  which  the  dates  appear  if  they  knew  what  it 
meant.  This  is  perhaps  rather  harsh  language,  but  a  good 
many  men  would  be  tempted  to  send  back  a  barrel  of  old 
batteries  every  now  and  then  with  the  covers  showing  that 
they  had  not  lasted  three  months,  if  they  could  read  these 
signatures. 

Practically  the  only  means  the  jeweler  has  of  obtaining  a 
good  cell,  with  long  life,  is  to  buy  them  of  a  large  electrical 
supply  house,  paying  a  good  price  for  them  and  making 
sure  that  that  house  has  trade  enough  in  that  battery  to 
insure  their  being  continuously  supplied  with  fresh  stock. 

The  position  of  the  battery  also  has  to  do  with  the  length 
of  life  or  amount  of  its  output.  Thus  a  battery  lying  on  its 
side  will  not  give  more  than  seventy-five  per  cent  of  the 
output  of  a  battery  which  is  standing  with  the  zinc  and 
carbon  elements  perpendicular.  Square  batteries  will  not 
give  the  satisfaction  that  the  round  cell  does.  It  has  been 
found  in  practice  by  trials  of  numerous  shapes  and  propor- 
tions that  the  ordinary  size  of  2}^x6  inches  will  give 
better  satisfaction  than  one  of  a  different  shape — wider  or 
shorter,  or  longer  and  thinner;  that  is  for  the  amount  of 
material  which  it  contains.  The  battery  which  has  proved 
most  successful  in  gas  engine  ignition  work  is  3^x8 
inches.  That  maintains  the  same  proportions  as  above,  or 
very  nearly  so,  but  owing  to  local  action  it  will  give  on 
clock  work  only  about  fifty  per  cent  longer  life  than  the 
smaller  size. 

It  has  been  a  more  or  less  common  experience  with 
purchasers  of  electric  clocks  to  find  that  the  batteries  which 
came  with  the  clock  from  the  factory  ran  for  two  or  three 
years   (three  years  not  being  at  all  uncommon)   and  that 


386 


THE    MODERN    CLOCK. 


they  were  then  unable  to  obtain  batteries  which  would 
stand  up  to  the  work  for  more  than  three  weeks,  up  to 
six  months.  The  difference  is  in  the  quality  and  freshness 
of  the  battery  bought,  as  outlined  above. 

In  considering  the  rest  of  the  electrical  circuit,  we  find 
three  methods  of  wiring  commonly  used  and  also  a  fourth 
which  is  just  now  coming  into  use.  The  majority  of  elec- 
tric clocks  are  wound  by  a  magnet  which  varies  in  size  from 
three   to   six  ohms ;    bridged   around  the   contact  points, 


HM 


RbO 


w^ 


Fig.  128. 


Fig.  129. 


there  has  generally  been  placed  a  resistance  spool  which 
varies  in  size  from  ten  to  twenty-five  times  the  number  of 
ohms  in  the  armature  magnets.  See  Fig.  128.  This  prac- 
tically makes  a  closed  circuit  on  which  we  are  using  a  bat- 
tery designed  for  open  circuit  work. 

If  we  use  an  electro-magnet  with  a  very  soft  iron  core, 
we  will  need  a  small  amount  of  current,  but  every  time  we 
break  the  contact,  we  will  have  a  very  high  counter  electro- 
motive force,  leaping  the  air  gap  made  while  breaking  the 


i 


THE    MODERN    CLOCK.  387 

contact  and  therefore  burning  the  contact  points.  If  our 
magnet  is  constructed  so  as  to  use  the  least  current,  by 
very  careful  winding  and  very  soft  iron  cores,  this  counter 
electro-motive  force  will  be  at  its  greatest  while  the  draft 
on  the  battery  is  at  its  smallest.  If  the  magnet  cores  are 
rhade  of  harder  iron,  the  counter  electro-motive  force  will 
be  much  less ;  but  on  the  other  hand  much  more  current 
will  be  needed  to  do  a  given  quantity  of  work  with  a  mag- 
net of  the  second  description;  and  the  consequence  is  that 
while  we  save  our  contact  points  to  some  extent,  we  deplete 
the  battery  more  rapidly. 

If  we  put  in  the  highest  possible  resistance — that  of  air — 
in  making  and  breaking  our  contacts,  we  use  current  from 
the  battery  only  to  do  useful  work;  but  we  also  have  the 
spark  from  the  counter  electro-motive  force  in  a  form 
which  will  destroy  our  contact  points  more  quickly.  If  we 
reduce  the  resistance  by  inserting  a  German  silver  wire  coil 
of  say  sixty  ohms  on  a  six-ohm  magnet  circuit,  we  have 
then  with  two  dry  batteries  (the  usual  number)  three  volts 
of  current  in  a  six-ohm  magnet  during  work  and  three  volts 
of  current  in  a  sixty-six  ohm  circuit  while  the  contacts  are 
broken,  Fig.  128.  Dividing  the  volts  by  the  ohms,  we  find 
that  one  twenty-second  of  an  ampere  is  constantly  flowing 
through  such  a  circuit.  We  are  therefore  using  a  dry 
battery  (an  open  circuit  battery)  on  closed  circuit  work  and 
we  are  drawing  from  the  life  of  our  battery  constantly  in 
order  to  save  our  contact  points. 

It  then  becomes  a  question  which  we  are  going  to  sacri- 
fice, or  what  sort  of  a  compromise  may  be  made  to  obtain 
the  necessary  work  from  the  magnet  and  at  the  same  time 
get  the  longest  life  of  the  contact  points  and  the  batteries. 
Most  of  the  earHer  electric  clocks  manufactured  have  finally 
arranged  such  a  circuit  as  has  been  described  above. 

The  Germans  put  in  a  second  contact  between  the  bat- 
tery and  the  resistance  with  a  little  larger  angular  motion 
than. the  first  or  principal  contact,  so  that  the  contact  is 


388 


THE    MODERN    CLOCK. 


then  first  made  between  the  battery  and  resistance  spool,  B, 
Fig.  129,  then  between  the  two  contact  points  of  the  shunt, 
A;  Fig.  129,  to  the  electro-magnet,  and  after  the  work  is 
done  they  are  broken  in  the  reverse  order,  so  that  the  resist- 
ance is  made  first  and  broken  after  the  principal  contact. 
This  involves  just  twice  as  many  contact  points  and  it  also 
involves  more  or  less  burning  of  the  second  contact. 


RbO 


w 


Fig.  130. 


Fig.  131. 


The  American  manufacturers  seem  to  prefer  to  waste 
more  or  less  current  rather  than  to  introduce  additional 
contact  points,  as  they  find  that  these  become  corroded  in 
time  with  even  the  best  arrangements  and  they  desire  as 
few  of  them  as  possible  in  their  movements,  preferring 
rather  to  stand  the  draft  on  the  battery. 

One  American  manufacturer  inserts  a  resistance  spool  of 
60  ohms  in  parallel  with  a  magnet  of  seven  ohms  (3^  ohms 
for  each  magnet  spool)  as  in  Fig.  130.  He  states  that  the 
counter  electro-motive  force  is  thus  dissipated  in  the  re- 
sistance when  the  contact  is  broken,  as  the  resistance  thus 
becomes  a  sort  of  condenser,  and  almost  entirely  does  away 


THE    MODERN'    CLOCK.  389 

with  heating  and  burning  of  the  contacts,  while  keeping  the 
circuit  open  when  the  battery  is  doing  no  work. 

It  has  been  suggested  to  the  writer  by  several  engineers 
of  high  attainments  and  large  experience  that  what  should 
be  used  in  the  above  combination  is  a  condenser  in  place  of 
a  resistance  spool,  as  there  would  then  be  no  expenditure  of 
current  except  for  work.  One  of  the  clocks  changed  to  this 
system  just  before  the  failure  of  its  manufacturers,  but  as 
less  than  four  hundred  clocks  were  made  with  the  con- 
densers (Fig.  131),  the  point  was  not  conclusively  demon- 
strated. 

It  should  also  be  borne  in  mind  that  the  condenser  has 
been  vastly  improved  within  the  last  twelve  months.  With 
the  condenser  it  will  be  observed  that  there  is  an  abso- 
lutely open  circuit  while  the  armature  is  doing  no  work 
and  that  therefore  the  battery  should  last  that  much  longer, 
Figs.  130  and  131.  As  to  the  cost  of  the  condensers  as 
compared  with  resistance  spools,  we  are  not  informed,  but 
imagine  that  with  the  batteries  lasting  so  much  longer  and 
the  clock  consequently  giving  so  much  better  satisfaction, 
a  slight  additional  cost  in  manufacture  by  changing  from 
resistance  to  condensers  would  be  welcomed,  if  it  added  to 
the  length  of  life  and  the  surety  of  operation. 

Electric  clocks  cost  more  to  make  than  spring  or  weight 
clocks  and  sell  for  a  higher  price  and  a  few  cents  additional 
per  movement  would  be  a  very  small  premium  to  pay  for  an 
increase  in  efficiency. 

The  repairer  who  takes  down  and  reassembles  one  of 
these  clocks  very  often  ignorantly  makes  a  lot  of  trouble  for 
himself.  Many  of  the  older  clocks  were  built  in  such  a  way 
that  the  magnets  could  be  shifted  for  adjustment,  instead 
of  being  put  in  with  steady  pins  to  hold  them  accurately  in 
place.  The  retail  jeweler  who  repairs  one  of  these  clocks  is 
apt  to  get  them  out  of  position  in  assembling.  The  arma- 
ture should  come  down  squarely  to  the  magnets,  but  should 
not  be  allowed  to  touch,  as  if  the  iron  of  the  armature 


390  THE    MODERN    CLOCK. 

touches  the  poles  of  the  magnet  it  will  freeze  and  retain 
its  magnetism  after  the  current  is  broken.  Some  manufac- 
turers avoid  this  by  plating  their  armatures  with  copper  or 
brass  and  this  has  puzzled  many  retailers  who  found  an 
electro-magnet  apparently  attracting  a  piece  of  metal  which 
is  generally  understood  to  be  non-magnetic. 

The  method  offers  a  good  and  permanent  means  of  in- 
sulating the  iron  of  the  armature  from  the  magnet  poles 
while  allowing  their  close  contact  and  as  the  strength  of  a 
magnet  increases  in  proportion  to  the  square  of  the  distance 
between  the  poles  and  the  armature,  it  will  be  seen  that 
allowing  the  armature  to  thus  approach  as  closely  as  pos- 
sible to  the  poles  greatly  increases  the  pull  of  the  magnet 
at  its  final  point.  If  when  setting  them  up  the  magnet  and 
armature  do  not  approach  each  other  squarely,  the  armature 
will  touch  the  poles  on  one  side  or  another  and  soon  wear 
through  the  copper  or  brass  plating  designed  to  maintain 
their  separation  and  then  we  will  have  freezing  with  its 
accompanying  troubles. 

A  very  good  test  to  determine  this  is  to  place  a  piece  of 
watch  paper,  cigarette  paper  or  other  thin  tissue  on  the 
poles  of  the  magnet  before  the  naked  iron  armature  is 
drawn,  down.  Then  make  the  connection,  hold  the  armature 
and  see  if  the  paper  can  be  withdrawn.  If  it  cannot  the 
armature  and  poles  are  touching  and  means  should  be 
taken  to  separate  them.  This  is  sometimes  done  by  driving 
a  piece  of  brass  into  a  hole  drilled  in  the  center  of  the  pole 
of  the  magnet;  or  by  soldering  a  thin  foil  of  brass  on  the 
armature.  As  long  as  the  separation  is  steadily  maintained 
the  object  sought  is  accomplished,  no  matter  what  means 
is  used  to  attain  it. 

Another  point  with  clocks  which  have  their  armatures 
moved  in  a  circular  direction  is  to  see  that  the  magnet  is  so 
placed  as  to  give  the  least  possible  freedom  betv^een  the 
armatures  and  the  circular  poles  of  the  magnet,  but  that 
there  must  be  an  air-gap  between  the  armature  and  magnet 
poles. 


THE    MODERN    CLOCK.  39I 

In  those  clocks  which  wind  a  spring  by  means  of  a  lever 
and  ratchet  working-  into  a  fine-toothed  ratchet  wheel,  or 
are  driven  by  a  weighted  lever,  there  is  an  additional  point 
to  guard  against.  If  the  weight  lever  is  thrown  too  far  up, 
either  one  of  two  things  will  happen.  The  weight  lever 
may  be  thrown  up  to  ninety  degrees  and  become  balanced 
if  the  butting  post  is  left  off  or  wrongly  replaced ;  the 
power  will  then  be  taken  off  the  clock,  if  it  is  driven  directly 
by  weight,  so  that  a  butting  post  should  meet  the  lever  at 
the  highest  point  and  insure  that  it  will  not  go  beyond  this 
and  thus  lose  the  efficiency  of  the  weight. 

In  the  cases  where  a  spring  on  the  center  arbor  is  inter- 
posed between  the  arbor  and  the  ratchet  wheel,  it  should  be 
determined  just  how  many  teeth  are  necessary  to  be  oper- 
ated when  winding,  as  if  a  clock  is  wound  once  an  hour 
and  the  aim  is  to  wind  a  complete  turn  (which  is  the  amount 
the  arbor  has  run  down)  if  the  lever  is  allowed  to  vibrate 
©ne  or  tw^o  teeth  beyond  a  complete  turn,  it  will  readily  be 
seen  that  in  the  course  of  time  the  spring  will  wind  itself 
so  tightly  as  to  break  or  become  set.  This  was  a  frequent 
fault  with  the  Dulaney  clock  and  has  not  been  guarded 
against  sufficiently  in  some  others  which  use  the  fine  ratchet 
tooth  for  winding. 

When  such  a  clock  is  found  the  proper  number  of  teeth 
should  be  ascertained  arid  the  rest  of  the  mechanism  ad- 
justed to  see  that  just  that  number  of  teeth  will  be  wound 
If  less  is  wound  there  will  come  a  time  when  the  spring 
will  run  down  and  the  clock  will  stop.  If  too  much  is 
wound  the  spring  will  eventually  become  set  and  the  clock 
will  stop.  Therefore  such  movements  should  be  examined 
to  see  that  the  proper  amount  of  winding  occurs  at  each 
operation.  Of  course  where  a  spring  is  wound  and  there 
are  but  four  notches  in  the  ratchet  wheel  and  the  screw  stop 
is  accurately  placed  to  stop  the  action  of  the  armature,  over 
action  will  not  harm  the  spring,  provided  it  will  not  go  to 
another  quarter,  as  if  the  armature  carries  the  ratchet  wheel 


39^ 


THE    MODERN    CLOCK. 


further  than  it  should,  the  smooth  circumference  between 
the  notches  will  let  it  drop  back  to  its  proper  notch. 

There  are  a  large  number  of  clocks  on  the  market  which 
wind  once  per  hour.  These  differ  from  the  others  in  that 
they  do  not  depend  upon  a  single  movement  of  the  arma- 
ture for  an  instantaneous  winding.  Thus  if  the  batteries 
are  weak  it  may  take  twenty  seconds  to  wind.  If  the  bat- 
teries are  strong  and  new  it  may  wind  in  six  seconds.  In 
this  respect  the  clock  differs  radically  from  the  others,  and 
while  we  have  not  personally  had  them  under  test,  we  are 
informed  that  on  account  of  winding  once  per  hour  the 
batteries  will  last  very  much  longer  than  would  be  expected 
proportionately  from  those  which  wind  at  periods  of  greater 
frequency.  The  reason  assigned  is  that  the  longer  period 
allows  the  battery  to  dispose  of  its  hydrogen  on  the  zinc 
and  thus  to  regain  its  energy  much  more  completely  between 
the  successive  discharges  and  hence  can  give  a  more  effect- 
ive quantity  of  current  for  hourly  discharge  than  those 
which  are  discharged  several  times  a  minute,  or  even  sev- 
eral times  an  hour.  It  is  only  proper  to  add  that  the  manu- 
facturers of  clocks  winding  every  six  or  seven  minutes 
dispute  this  assertion. 

Another  point  is  undoubtedly  in  the  increased  length  of 
life  of  the  contacts;  but  speaking  generally  the  electric 
clock  may  be  said  now  to  be  waiting  for  further  improve- 
ments in  the  batteries.  Those  who  have  had  the  greatest 
experience  with  batteries,  as  the  telephone  companies,  tele- 
graph companies  and  other  public  service  corporations,  have 
generally  discarded  their  use  in  favor  of  storage  batteries 
and  dynamos  wherever  possible  and  where  this  is  not  pos- 
sible they  have  inspected  them  continuously  and  regularly. 

In  this  respect  one  point  will  be  found  of  great  service. 
When  putting  in  a  new  set  of  batteries  in  any  electrical 
piece  of  machinery,  write  the  date  in  pencil  on  the  battery 
cover,  so  that  you,  or  those  who  come  after  you,  some  time 
later,  will  know  the  exact  length  of  time  the  battery  has 


THE    MODERN    CLOCK.  393 

been  in  service.  This  is  frequently  of  importance,  as  it 
will  determine  very  largely  whether  the  battery  is  playing 
out  too  soon,  or  whether  faults  are  being  charged  to  the 
battery  which  are  really  due  to  other  portions  of  the  ap- 
paratus. 

Never  put  together  any  piece  of  electrical  apparatus  with- 
out seeing  that  all  parts  are  solidly  in  position  and  are 
clean ;  always  look  carefully  to  connections  and  see  that  the 
insulation  is  perfect  so  that  short  circuits  will  be  impossible. 

All  contacts  must  be  kept  smooth  and  bright  and  contact 
must  be  made  and  broken  without  any  wavering  or  uncer- 
tainty. 

Fig.  132  shows  the  completely  wired  movement  of  the 
American  Clock  Company's  weight-driven  movement,  which 
may  be  accepted  as  a  type  of  this  class  of  movements — > 
weight-driven,  winding  every  seven  minutes. 

The  train  is  a  straight-line  time  train,  from  the  center 
arbor  to  the  dead  beat  escapement,  with  the  webs  of  the 
wheels  not  crossed  out.  It  is  wired  with  the  wire  from  the 
battery  zinc  screwed  to  the  front  plate  H  and  that  from 
the  battery  carbon  to  an  insulated  block  G. 

Fig.  133  shows  an  enlarged  view  of  the  center  arbor. 
Upon  this  arbor  are  secured  (friction  tight)  two  seven- 
notched  steel  ratchets,  E,  and  carried  loosely  between  them 
are  two  weighted  levers  pivoted  loosely  on  the  center  arbor. 
Each  lever  is  provided  with  a  pawl  engaging  in  the  notches 
of  the  nearest  ratchet,  as  shown.  The  weighted  lever  has 
a  circular  slot  cut  in  it,  concentric  with  the  center  hole  and 
also  has  a  portion  of  its  circumference  at  the  arbor  cut 
away,  thus  forming  a  cam.  Between  these  two  levers  is  a 
connecting  link  D  with  a  pin  in  its  upper  end,  which  pin 
projects  into  the  circular  slots  of  the  weight  levers. 

The  lever  F  is  pivoted  to  the  front  plate  of  the  clock  and 
carries  at  right  angles  a  beveled  arm  which  projects  over 
the  ratchets  E,  but  is  ordinarily  prevented  from  dropping 
into  the  notches  by   riding  on  the  circumferences  of  the 


394 


THE    MODERN    CLOCK. 


o  O 

CO  O  CO 

oc  2  of 

2  N  CONNECTING  WIRE      S 


jH  ^rMggwriHi'^ 


Fig.  132 


THE    MODERN    CLOCK. 


395 


weighted  levers.  When  one  lever  has  dropped  down  and 
the  other  has  reached  a  horizontal  position  the  cut  portions 
of  the  circumferences  of  these  levers  will  be  opposite  the 
upper  notch  of  the  ratchets  and  will  allow  the  bar  project- 


Fig.  133 


ing  from  F  to  drop  into  the  notches.  This  allows  F  and  G 
to  connect  and  the  magnet  A  is  energized,  pulls  the  arma- 
ture B,  the  arms  C  D,  and  thus  lifts  the  lever  through  the 
pin  in  D  pulling  at  the  end  of  the  circular  slot.  As  the 
lever  flies  upward,  the  cam-shaped  portion  of  its  circum- 


39^ 


THE    MODERN    CLOCK. 


ference  raises  the  arm  out  of  the  notches,  thus  separating 
F  and  G  and  breaking  the  circuit.  A  spring  placed  above 
E  keeps  its  arms  pressed  constantly  upon  E  in  position  to 
drop.    The  wiring  of  the  magnets  is  shown  in  Fig.  130. 

The  upper  contact  (carried  in  F)  is  a  piece  of  platinum 
with  its  lower  edge  cut  at  an  angle  of  fifteen  degrees  and 
beveled  to  a  knife-edge.  The  lower  point  of  this  bevel 
comes  into  contact  first  and  is  the  last  to  separate  when 
breaking  connection,  so  that  any  sparking  which  may  take 
place  will  be  confined  to  one  edge  of  the  contacts  while  the 
rest  of  the  surface  remains  clean.     (See  Fig.  134.)     Ordi- 


^^ 


Fig.  134 

narily  there  is  very  little  corrosion  from  burning  and  this  is 
constantly  rubbed  off  by  the  sliding  of  the  surfaces  upon 
each  other.  The  lower  contact,  G,  consists  of  a  brass  block 
mounted  upon  an  insulating  plate  of  hard  rubber.  The 
block  is  in  two  pieces,  screwed  together,  and  each  piece 
carries  a  platinum  tipped  steel  spring.  These  springs  are 
so  set  as  to  press  their  platinum  tips  against  each  other  di- 
rectly beneath  the  upper  contact.  The  upper  and  lower 
platinum  tips  engage  each  other  about  one-sixteenth  inch  at 
the  time  of  making  contact.  The  lower  block  being  in  two 
pieces,  the  springs  may  be  taken  apart  for  cleaning,  or  to 
adjust  their  tension.    The  latter  should  be  slight  and  should 


THE    MODERN    CLOCK.  397 

in  no  case  exceed  that  which  is  exerted  by  the  spring  in 
F,  or  the  upper  knife-edge  will  not  be  forced  between  the 
two  lower  springs.  The  pin  on  which  F  is  pivoted  and  that 
bearing  on  the  spring  above  it  must  be  clean  and  bright  and 
never  he  oiled,  as  it  is  through  these  that  the  current  passes 
to  the  upper  contact  in  the  end  of  F.  The  contacts  are,  of 
course,  never  oiled. 

The  two  weighted  levers  should  be  perfectly  free  on  the 
center  arbor  and  their  supporting  pawls  should  be  perfectly 
free  on  the  shoulder  screws  in  the  levers.  Their  springs 
should  be  strong  enough  to  secure  quick  action  of  the 
pawls.  This  freedom  and  speed  of  action  are  important, 
as  the  levers  are  thrown  upward  very  quickly  and  may  re- 
bound from  the  butting  post  without  engaging  the  ratchets 
if  the  pawls  do  not  work  quickly. 

The  projecting  arm,  C,  of  the  armature,  B,  has  pivoted 
to  it,  a  link,  D,  which  projects  upward  and  supports  at  its 
upper  end  a  cross  pin.  The  link  should  not  be  tight  in  the 
slot  of  C,  but  should  fit  closely  on  the  sides,  in  order  to 
keep  the  cross  pin  at  the  top  of  D  parallel  with  the  center 
staff  of  the  clock.  This  cross  pin  projects  through  D  an 
equal  distance  on  either  side,  each  end  respectively  passing 
through  the  slot  of  the  corresponding  lever,  the  total  length 
of  this  pin  being  nearly  equal  to  the  distance  between  the 
ratchets.  When  the  electric  circuit  is  closed,  and  the  mag- 
nets energized,  B,  C  and  D  are  drawn  downward;  the 
weighted  end  of  one  of  the  levers  which  runs  the  clock, 
being  at  this  time  at  the  limit  of  its  downward  movement, 
see  Fig.  135,  the  opposite  or  slotted  end  of  said  lever,  is 
then  at  its  highest  point,  and  the  downward  pull  in  the 
slot  by  one  end  of  the  above  described  crosspin  which  en- 
ters it  will  throw  the  weighted  end  of  the  said  lever  upward. 
The  direct  action"  of  the  magnets  raises  the  lever  nearly  to 
the  horizontal  position,  and  the  momentum  acquired  carries 
it  the  remainder  of  the  distance.  By  this  arrangement  of 
stopping  the  downward  pull  of  the  pin  when  the  ascending 


398 


THE    MODERN    CLOCK. 


lever  reaches  the  horizontal,  all  danger  of  disturbing  the 
other  lever  A  is  avoided.  The  position  is  such  that  the  top 
of  the  ascending  lever  weight  is  about  even  with  the  center 
of  the  other  weight  when  the  direct  pull  ceases. 


Fig.  135 


Before  starting  the  clock  raise  the  lever  weights  so  that 
one  lever  is  acting  upon  a  higher  notch  of  the  ratchet  than 
the  other.  They  are  designed  to  remain  about  forty-five 
degrees  apart,  so  as  to  raise  only  one  lever  at  each  action  of 
the  magnet.  This  maintains  an  equal  weight  on  the  train, 
which  would  not  be  the  case  if  they  were  allowed  to  rise 
and  fall  together ;  keeping  the  levers  separated  also  reduces 
the  amount  of  lift  or  pull  on  the  battefy  and  uses  less  cur- 


THE    MODERN    CLOCK.  399 

rent,  which  Is  an  item  when  the  battery  is  nearly  run  down. 
If  these  levers  are  found  together  it  indicates  that  the  bat- 
tery is  weak,  the  contacts  dirty,  making  irregular  winding, 
or  the  pawls  are  working  improperly.  See  that  the  levers 
rise  promptly  and  with  sufficient  force.  After  one  of  them 
has  risen  stop  the  pendulum  and  see  that  the  butting  post 
is  correctly  placed,  so  that  there  is  no  danger  of  the  lever 
wedging  under  the  post  and  sticking  there,  or  causing  the 
lever  to  rebound  too  much.  The  butting  post  is  set  right 
when  the  clock  leaves  the  factory  and  seldom  needs  adjust- 
ment unless  some  one  has  tinkered  with  it. 

The  time  train  should  be  oiled  as  with  the  ordinary  move- 
ments, also  the  pawls  on  the  levers.  The  lever  bushings 
should  be  cleaned  before  oiling  and  then  well  oiled  in  order 
to  avoid  friction  on  the  center  arbor  from  the  downward 
pull  of  the  magnets  when  raising  the  levers.  In  order  to 
clean  the  levers  drive  out  the  taper  pin  in  the  center  arbor 
and  remove  the  front  ratchet,  when  the  levers  will  slip  off. 
In  putting  them  back  care  should  be  used  to  see  that  the 
notches  of  the  ratchets  are  opposite  each  other.  Oil  the 
edges  of  the  ratchets  and  the  armature  pins.  Do  not  under 
any  circumstances  oil  the  contact  points,  the  pins  or  springs 
of  the  bar  F,  as  this  will  destroy  the  path  of  the  current 
and  thus  stop  the  clock.  These  pins  must  be  kept  clean 
and  bright. 

Hourly  Winding  Clocks. — There  are  probably  more  of 
these  in  America  than  of  all  other  electric  kinds  put  to- 
gether (we  believe  the  present  figures  are  something  like 
135,000),  so  that  it  will  not  be  unreasonable  to  give  consid- 
erable space  to  this  variety  of  clocks.  Practically  all  of 
them  ar€  made  by  the  Self  Winding  Clock  Company  and 
are  connected  with  the  Western  Union  wires,  being  wound 
by  independent  batteries  in  or  near  the  clock  cases. 

Three  patterns  of  these  clocks  have  been  made  and  we 
will  describe  all  three.     As  they  are  all  practically  in  the 


400  THE    MODERN    CLOCK. 

same  system,  it  will  probably  be  better  to  first  make  a 
simple  statement  of  the  wiring,  which  is  rigidly  adhered  to 
by  the  clock  company  in  putting  out  these  goods.  All  wires 
running  from  the  battery  to  the  winding  magnets  of  the 
movement  are  brown.  All  wires  running  from  the  syn- 
chronizing magnet  to  the  synchronizing  line  are  blue.  Mas- 
ter clocks  and  sub-master  clocks  have  white  wires  for  re- 
ceiving the  Washington  signal  and  the  relay  for  closing  the 
synchronizing  line  will,  have  wires  of  blue  and  white  plaid. 


Fig.  136 

By  remembering  this  system  it  is  comparatively  easy  for 
a  man  to  know  what  he  is  doing  with  the  wires,  either 
inside  or  outside  of  the  case.  For  calendar  clocks  there  are, 
in  addition,  two  white  wires  running  from  the  calendar  to 
the  extra  cell  of  battery.  There  is  also  one  other  peculiar- 
ity, in  that  these  clocks  are  arranged  to  be  wound  by  hand 
whenever  run  down  (or  when  starting  up)  by  closing  a 
switch  key,  shown  in  Fig.  136,  screwed  to  the  inside  of  the 
case.  This  is  practically  an  open  switch,  held  open  by  the 
spring  in  the  brass  plate,  except  when  it  is  pressed  down  to 
the  lower  button. 

The  earliest  movement  of  which  any  considerable  number 
were  sent  out  was  that  of  the  rotary  winding  from  a  three- 
pole  motor,  as  shown  in  Fig.  137.  Each  of  these  magnet 
spools  is  of  two  ohms,  with  twelve  ohms  resistance,  placed 
in  parallel  with  the  winding  of  each  set  of  magnet  spools, 
thus  making  a  total  of  nine  spools  for  the  three-pole 
motor. 

On  the  front  end  of  the  armature  drum  arbor  is  a  com- 
mutator having  six  points,  corresponding  to  the  six  arma- 


THE    MODERN    CLOCK, 


401 


Fig.  137 


402  THE    MODERN    CLOCK. 

tures  in  the  drum.  There  are  three  magnets  marked  O, 
P  and  X;  each  magnet  has  its  own  brush  marked  O',  P' 
and  X'.  When  an  armature  approaches  a  magnet  (see  Fig. 
137)  the  brush  makes  contact  with  a  point  of  the  com- 
mutator, and  remains  in  contact  until  the  magnet  has  done 
its  work  and  the  next  magnet  has  come  into  action.  When 
properly  adjusted  the  brush  O'  will  make  contact  when 
armatures  i  and  2  are  in  the  position  shown,  with  No.  2  a 
little  nearer  the  core  of  the  magnet  than  No.  i ;  and  it  will 
break  contact  when  the  armature  has  advanced  into  the 
position  shown  by  armature  No.  3,  the  front  edge  of  the 
armature  being  about  one-sixteenth  of  an  inch  from  the 
corner  of  the  core,  armature  No.  4 .  being  entirely  out  of 
circuit,  as  brush  X'  is  not  touching  the  commutator. 

The  back  stop  spring,  S,  Fig.  137,  must  be  adjusted  so 
that  the  brush  O'  is  in  full  contact  with  a  point  of  the 
commutator  when  the  motor  is  at  rest,  with  a  tooth  of  the 
ratch  touching  the  end  of  the  spring,  S. 

Sometimes  the  back  stop  spring,  S,  becomes  broken  or 
bent.  When  this  occurs  it  is  usually  from  overwinding.  It 
must  be  repaired  by  a  new  spring,  or  by  straightening  the 
old  one  by  burnishing  with  a  screwdriver.  Set  the  spring 
so  that  it  will  catch  about  half  way  dotvn  the  last  tooth. 

Having  explained  the  action  of  the  motor  we  come  now 
to  the  means  of  temporarily  closing  the  circuit  and  keeping 
it  closed  until  such  time  as  the  spring  is  wound  a  suffi- 
cient amount  to  run  the  clock  for  one  hour;  as  the  spring 
is  on  the  center  arbor  this  requires  one  complete  turn. 

This  is  the  distinguishing  feature  of  this  system  of  clocks 
and  is  not  possessed  by  any  of  the  others.  It  varies  in  con- 
struction in  the  various  movements,  but  in  all  its  forms  it 
maintains  the  essential  properties  of  holding  the  current  on 
to  the  circuit  until  such  time  as  the  spring  has  been  wound 
a  sufficient  quantity,  when  it  is  again  forcibly  broken  by  the 
action  of  the  clock.  This  is  termed  the  "knock  away,"  and 
exists  in  all  of  these  movements. 


THE    MODERN    CLOCK.  403 

To  start  the  motor  the  circuit  is  closed  by  a  platinum 
tipped  arm,  A,  Fig.  138,  loosely  mounted  on  the  center 
arbor,  and  carried  around  by  a  pin  projecting  from  the 
center  wheel  until  the  arm  is  upright,  when  it  makes  con- 
tact with  the  insulated  platinum  tipped  brush,  B.  A  carries 
in  its  front  an  ivory  piece  which  projects  a  trifle  above  the 
platinum  top,  so  that  when  B  drops  off  the  ivory  it  will 
make  contact  with  the  platinum  on  A  firmly  and  suddenly. 
This  contact  then  remains  closed  until  the  spring  barrel  is 
turned  a  full  revolution,  when  a  pin  in  the  barrel  cover 
brings  up  the  "knock  away,"  C,  which  moves  the  arm.  A, 
forward  from  under  the  brush,  B,  and  breaks  the  circuit. 
The  brush,  B,  should  He  firmly  on  its  banking  piece,  and 
should  be  so  adjusted  that  when  it  leaves  the  arm.  A,  it  will 
drop  about  one-thirty-second  of  an  inch.  Adjusted  in  this 
way  it  insures  a  good,  firm  contact. 

The  angle  at  the  top  of  the  brush,  B,  must  not  be  too 
abrupt,  so  as  to  retard  the  action  of  the  clock  while  the 
contact  is  being  made.  Wire  No.  8  connects  the  spring 
contact,  B,  to  one  of  the  binding  plates  at  the  left-hand 
side  of  the  case ;  and  wire  No.  6  connects  the  motor,  M,  to 
the  other.  To  these  binding  plates  are  attached  brown 
wires  that  lead  one  to  each  end  of  the  battery. 

When  the  clock  is  quite  run  down,  it  is  wound  by  press- 
ing the  switch  key,  Fig.  136,  from  which  a  wire  runs  to  the 
plate.  The  switch  key  should  not  be  permanently  connected 
to  its  contact  screw,  J.  See  that  all  wires  are  in  good  con- 
dition and  all  connections  tight  and  bright.  The  main 
spring  is  wound  by  a  pinion  on  the  armature  drum  arbor, 
through  an  intermediate  wheel  and  pinion  to  the  wheel 
on    the    spring   barrel. 

At  stated  times — say  once  in  eighteen  months  or  two 
years — all  clocks  should  be  thoroughly  cleaned  and  oiled, 
and  at  the  same  time  inspected  to  be  sure  they  are  in  good 
order. 


404 


THE    MODERN    CLOCK. 


Never  let  the  self-winding  clocks  run  down  backward, 
as  the  arm,  A,  Fig.  138,  will  be  carried  back  against  the 
brush,  B,  and  bend  it  out  of  adjustment. 


Fig.  138 


To  clean  the  movement,  take  it  from  the  case,  take  out 
the  anchor  and  allow  it  to  run  down  gently,  so  as  not  to 
break  the  piiis^  then  remove  the  motor.  Take  ofif  the 
front  plate  and  separate  all  the  parts.  Never  take  off  the 
back  plate  in  these  clocks.  Wash  the  plates  and  all  parts  in 
a  good  quality  of  benzine,  pegging  out  the  holes  and  let- 
ting them  dry  thoroughly  before  reassembling.  The  motor 
must  not  be  taken  apart,  but  may  be  washed  in  benzine, 
by   using  a  small  brush   freely   about   the  bearings,   com- 


THE    MODERN    CLOCK.  4O5 

mutator  and  brushes.  Put  oil  in  all  the  pivot  holes,  but  not 
so  much  that  it  will  run.  The  motor  bearings  and  the  pal- 
lets of  the  anchor  should  also  be  oiled. 

Inspect  carefully  to  see  that  the  center  winding  con- 
tact is  right  and  that  the  motor  is  without  any  dead  points. 
Dust  out. the  case  and  put  the  movement  in  place.  Before 
putting  on  the  dial  try  the  winding  by  means  of  the  switch, 
Fig.  136,  to  be  sure  that  it  is  right;  also  see  that  the  disc 
on  the  cannon  socket  is  in  the  right  position  to  open  the 
latch  at  the  hour,  and  after  the  dial  and  hands  are  on  move 
the  minute  hand  forward  past  the  hour  and  then  backward 
gently  until  it  is  stopped  by  the  latch.  This  will  prove 
that  the  hand  is  on  the  square  correctly. 

On  account  of  the  liability  of  the  motor  to  get  out  of 
adjustment  and  fail  to  wind,  from  the  shifting  of  the 
springs  and  brushes,  under  careless  adjustment,  various  at- 
tempts have  been  made  to  improve  this  feature  of  these 
clocks  and  the  company  is  now  putting  out  nearly  alto- 
gether one  of  the  two  vibrating  motors,  shown  in  Figs. 
139  and  140. 

In  Style  C,  Fig.  139,  the  hourly  contact  for  winding  is  the 
same  as  in  the  clock  with  the  three-magnet  motor,  as  shown 
in  Fig.  138.  The  magnet  spools  are  twelve  ohms  and  the 
resistance  coil  is  eighty  ohms,  placed  in  parallel,  as  de- 
scribed in  Fig.  130. 

The  vibrating  motor,  Fig.  139,  is  made  with  a  pair  of 
magnets  and  a  vibrating  armature.  The  main  spring  is 
wound  by  the  forward  and  backward  motion  of  the  arma- 
ture, one  end  of  the  connecting  rod,  8,  being  attached 
to  a  lug  of  the  armature,  2,  and  the  other  to  the  winding 
lever,  10.  This  lever  has  spring  ends,  to  avoid  shock  and 
noise.  As  the  winding  lever  is  moved  up  and  down,  the 
pawl,  9,  turns  the  ratch  wheel,  11,  and  a  pinion  on  the 
ratch  wheel  arbor  turns  the  spring  barrel  until  the  winding 
is  completed. 


4o6 


THE    MODERN    CLOCK. 


Fig.  139 


THE    MODERN    CI>OCK,  407 

The  contact  for  operating  the  motor  is  made  by  the  brass 
spiral  spring,  3,  which  is  attached  to  the  insulated  stud,  4, 
and  the  platinum  pin,  5,  which  is  carried  on  a  spring  at- 
tached to  the  clock  plate.  As  the  armature  moves  forward 
the  break  pin,  A,  in  the  end  of  the  armature  lifts  the  con- 
tact spring,  3,  thus  breaking  the  circuit.  The  acquired  mo- 
mentum carries  the  armature  forward  until  it  strikes  the 
upper  banking  spring,  6,  when  it  returns  rapidly  to  its 
original  position,  banking  on  spring  7,  by  which  time  con- 
tact is  again  made  between  springs  3  and  5  and  the  vibra- 
tion is  repeated  until  the  clock  is  wound  one  turn  of  the 
barrel  and  the  circuit  is  broken  at  the  center  winding 
contact. 

Fig.  140,  Style  F,  is  a  similar  motor  so  far  as  the  vibrat- 
ing armature  and  the  winding  is  concerned,  but  the  wind- 
ing lever  is  pivoted  directly  on  the  arbor  of  the  winding 
wheel  and  operates  vertically  from  an  arm  and  stud  on  the 
armature  shaft,  working  in  a  fork  of  the  winding  lever,  8, 
Fig.  140.  It  will  be  seen  that  the  train  and  the  motor 
winding  mechanism  are  combined  in  one  set  of  plates.  The 
motor  is  of  the  oscillating  type  and  its  construction  is  such 
that  all  its  parts  may  be  removed  without  dissembling  the 
iclock  train. 

Construction  of  the  Motor. — The  construction  of  the 
motor  is  very  simple,  having  only  one  pair  of  magnets,  but 
two  sets  of  make  and  break  contacts,  one  set  of  which  is 
placed  on  the  front  and  the  other  on  the  back  plate  of  the 
movement,  thus  ensuring  a  more  reliable  operation  of  the 
motor,  and  reducing  by  fifty  per  cent  the  possibility  of  its 
failing  to  wind. 

The  center  winding  contact  also  differs  from  those  used 
in  the  three-magnet  motors  and  former  styles  of  vibrating 
motor  movements.  The  center  winding  contact  piece,  13, 
has  no  ivory  and  no  platinum.  The  hourly  circuit  is  not 
closed  by  the  current  passing  through  this  piece,  but  it  acts 


4o8 


THE    MODERN    CLOCK. 


by  bringing  the  plate  contact  spring,  i6,  in  metallic  connec- 
tion with  the  insulated  center-winding  contact  spring,  .17, 
both  of  which  are  platinum  tipped.  It  will  thus  be  seen 
that  no  accumulation  of  dirt,  oil  or  gum  around  the  center 
arbor  or  the  train  pivots  will  have  any  effect  in  preventing 
the  current  from  passing  from  the  motor  to  the  hourly  cir- 
cuit closer. 


Fis.  140 


The  operation  is  as  follows :  As  the  train  revolves,  the 
pin,  12,  securely  fastened  to  the  center  arbor,  in  its  hourly 
revolution  engages  a  pin  on  the  center  winding  contact 
piece,  13.  This  piece  as  it  revolves  pushes  the  plate  con- 
tact spring,  16,  upward,  bringing  it  in  metallic  connection 
with  the  center  winding  contact  spring,  17,  which  is 
fastened  to  a  stud  on  an  insulated  binding  post,  18,  thereby, 
closing  the  hourly  circuit.  The  current  passes  from  the 
binding  post,  18,  through  the  battery  (or  any  other  source 
of  current  supply)  to  binding  post  19,  to  which  is  connect- 


THE    MODERN    CLOCK.  409 

ed  one  end  of  the  motor  magnet  wire.  The  current  passes 
through  these  magnets  to  the  insulated  stud,  4.  To  this 
stud  the  spiral  contact  spring,  3,  is  fastened  and  the  cur- 
rent passes  from  this  spring  to  the  plate  contact  spring,  5, 
thence  through  the  movement  plate  to  plate  contact  spring, 
16,  and  from  there  through  spring,  17,  back  to  the  battery. 

The  main  spring  is  wound  by  the  forward  and  backward 
motion  of  the  armature,  2.  To  this  armature  is  connected 
the  winding  lever,  8.  As  the  winding  lever  is  oscillated,  the 
pawl,  9,  turns  the  ratchet  wheel,  11,  and  a  pinion  on  the 
ratchet  wheel  arbor  turns  the  winding  wheel  until  the  pin, 
15,  connected  to  it  engages  the  knock-away  piece,  14,  re- 
volving it  until  it  strikes- the  pin  on  the  center  winding 
contact  piece,  13,  and  pushes  it  from  under  the  plate  contact 
spring,  thereby  breaking  the  electric  circuit  and  completing 
the  hourly  winding. 

The  proper  position  of  the  contact  springs  is  clearly  indi- 
cated in  Fig.  140.  The  spring,  16,  should  always  assume 
the  position  shown  thereon.  When  the  center  winding 
contact  piece,  13,  comes  in  metallic  connection  with  the 
plate  contact  spring,  16,  the  end  of  this  spring  should 
stand  about  one-thirty-second  of  an  inch  from  the  edge 
of  the  incline.  The  center  winding  contact  spring,  17, 
should  always  clear  the  plate  contact  spring  one-thirty- 
second  of  an  inch.  When  the  two  springs  touch  they 
should  be  perfectly  parallel  to  each  other. 

Adjustments  of  the  Armature. — In  styles  C  and  F, 
when  the  armature,  2,  rests  on  the  banking  spring,  7,  its 
front  edge  should  be  in  line  with  the  edge  of  the  magnet 
core.  The  upper  banking  spring,  6,  must  be  adjusted  so 
that  the  front  edge  of  the  armature  will  be  one-sixteenth  of 
an  inch  from  the  corner  of  the  magnet  core  when  it  touches 
the  spring. 

When  the  contact  spring,  3,  rests  on  the  platinum  pin,  5, 
it  should  point  to  about  the  center  of  the  magnet  core,  with 


4IO  THE    MODERN    CLOCK. 

the  platinum  pin  at  the  middle  of  the  platinum  piece  on  the 
spring. 

To  adjust  the  tension  of  the  spiral  contact  spring,  3,  take 
hold  of  the  point  with  a  light  pair  of  tweezers  and  pull  it 
gently  forward,  letting  it  drop  under  the  pin.  It  should 
take  the  position  shown  by  the  dotted  line,  the  top  of  the 
spring  being  about  one-thirty-second  of  an  inch  below  the 
platinum  pin.  If  from  any  cause  it  has  been  put  out  of  ad- 
justment it  can  be  corrected  by  carefully  bending  under  the 
tweezers,  or  the  nut,  4,  may  be  loosened  and  the  spring 
removed.  It  may  then  be  bent  in  its  proper  shape  and 
replaced. 

The  hole  in  the  brass  hub  to  which  the  spring  is  fastened 
has  a  flat  side  to  it,  fitting  a  flat  on  the  insulated  contact 
stud.  If  the  contact  spring  is  bent  to  the  right  position  it 
may  be  taken  off  and  put  back  at  any  time  without  chang- 
ing the  adjustment,  or  a  defective  spring  may  readily  be 
replaced  with  a  new  one.  When  the  armature  touches  the 
upper  banking  spring  the  spiral  contact  spring,  3,  should 
clear  the  platinum  pin,  5,  about  one-sixteenth  of  an  inch. 
Both  contacts  on  front  and  back  plates  in  style  F  are  ad- 
justed alike.  The  circuit  break  pins  "A"  on  the  armature 
should  raise  both  spiral  contact  sprmgs  at  the  same  instant. 

If  for  any  reason  the  motor  magnets  have  become  dis- 
placed they  may  readily  be  readjusted  by  loosening  the 
four  yoke  screws  holding  them  to  the  movement  plates. 
Hold  the  armature  against  the  upper  banking  spring,  move 
the  magnets  forward  in  the  elongated  slot,  20,  until  the 
ends  of  the  magnet  cores  clear  the  armature  by  one-sixty- 
fourth  of  an  inch,  then  tighten  down  the  four  yoke  screws. 
Connect  the  motor  to  the  battery  and  see  that  the  arma- 
ture has  a  steady  vibration  and  does  not  touch  the  magnet 
core.  The  adjustment  should  be  such  that  the  armature 
can  swing  past  the  magnet  core  one-eighth  to  three-six- 
teenths of  an  inch. 


THE    MODERN    CI.OCK.  4II 

Description  of  Synchronizer. — At  predetermined 
times  a  current  is  sent  through  the  synchronizer  magnet, 
D',  Fig.  141,  which  actuates  the  armature,  E,  to  which  arc 
attached  the  levers,  F  and  G,  moving  them  down  until  tlic 
points  on  the  lever,  G,  engage  with  two  projections,  4  and 
5,  on  the  minute  disc;  and  lever  F  engages  with  the 
heart-shaped  cam  or  roll  on  the  seconds  arbor  sleeve, 
causing  both  the  minute  and  second  hands  to  point  to  XII. 
These  magnet  spools  are  wound  to  twelve  ohms,  w^ith  an 
eighty-ohm  resistance  in  parallel. 

On  the  latch,  L,  is  a  pin,  I,  arranged  to  drop  under  the 
hook,  H,"  and  prevent  any  action  of  the  synchronizing 
levers,  except  at  the  hour.  A  pin  in  the  disc  on  the  can- 
non socket  unlocks  the  latch  about  two  minutes  before  the 
hour  and  closes  it  again  about  two  minutes  after  the  signal. 
This  is  to  prevent  any  accidental  ''cross"  on  the  synchron- 
izing line  from  disturbing  the  hands  during  the  hour. 

AI  is  a  Hght  spring  attached  to  the  synchronizing  frame 
to  help  start  the  armature  back  after  the  hands  are  set. 
The  wires  from  the  synchronizing  magnet  are  connected  to 
binding  plates  at  the  right-hand  side  of  the  clock  and  from 
these  binding  plates  the  blue  wires,  Nos.  9  and  10,  pass  out 
at  the  top  of  the  case  to  the  synchronizing  line. 

If  the  clock  gets  out  of  the  synchronizing  range  it  gen- 
erally indicates  very  careless  regulation.  The  clock  is  regu- 
lated by  the  pendulum,  as  in  all  others,  but  there  is  one 
peculiarity  in  that  the  pendulum  regulating  nut  has  a 
check  nut. 

If  the  clock  gains  time  turn  the  large  regulating  nut 
under  the  pendulum  bob  slightly  to  the  left. 

If  the  clock  loses  time  turn  the  nut  slightly  to  the 
right. 

Loosen  the  small  check  nut  under  the  regulating  nut 
before  turning  the  regulating  nut,  and  be  sure  to  tighten 
the  check  nut  after  moving  the  regulating  nut. 


412 


THE    MODERN    CLOCK. 


Fig.  141 


THE    MODERN    CLOCK.  413 

The  friction  of  the  seconds  hand  is  very  carefully  ad- 
justed at  the  factory,  being  weighed  by  hanging  a  small 
standard  weight  on  the  point  of  the  hand.  If  it  becomes 
too  light  and  the  hand  drives  or  slips  backward,  losing 
time,  it  can  be  made  stronger  by  laying  it  on  a  piece  of 
wood  and  rubbing  the  inner  sides  of  the  points  with  a 
smooth  screw  driver,  and  if  too  heavy  and  the  clock  will 
not  set  when  the  synchronizing  magnets  are  actuated,  the 
points  of  the  spring  in  the  friction  may  be  straightened  a 
little. 

If  the  seconds  hand  sleeve  does  not  hold  on  the  seconds 
socket,  pinch  it  a  little  with  pliers.  If  the  seconds  hand  is 
loose  on  the  sleeve  put  on  a  new  one  or  solder  it  on  the 
under  side. 

In  style  F  the  synchronizing  lever,  heart-shaped  sec- 
onds socket  and  cams  on  the  cannon  sockets  are  the  same 
as  in  the  old  style  movements,  shown  in  Fig.  141.  The 
difference  is  in  the  synchronizing  magnets  and  the  way 
they  operate  the  synchronizing  lever.  The  magnet  has 
a  flat  ended  core  instead  of  being  eccentric  like  the  former 
ones.  The  armature  is  also  made  of  flat  iron  and  is  pivoted 
to  a  stud  fastened  to  the  synchronizing  frame.  The  arma- 
ture is  connected  to  the  synchronizing  lever  by  a  connect- 
ing rod  and  pitman  screws.  A  sector  has  an  oblong  slot, 
allowing  the  armature  to  be  lowered  or  raised  one-six- 
teenth of  an  inch.  The  synchronizing  lever  is  placed  on  a 
steel  stud  fastened  to  the  front  plate  and  held  in  position 
by  a  brass  nut.  The  synchronizing  magnets  are  12  ohms 
with  80  ohms  resistance  and  are  fastened  to  a  yoke  which 
is  screwed  to  the  synchronizing  frame  by  four  iron  screws. 
The  holes  in  the  synchronizing  frame  are  made  oblong, 
allowing  the  yoke  and  magnets  to  be  raised  or  lowered  one- 
sixteenth  of  an  inch.  The  spring  on  top  of  the  armature 
is  used  to  throw  it  back  quickly  and  also  acts  as  a  diamag- 
netic,  preventing  the  armature  from  freezing  to  the  mag- 
nets.   A  screw  in  the  stud  is  used  to  screw  up  against  the 


414  THE    MODERN    CLOCK. 

magnet  head,  preventing  any  spring  that  might  take  place 
on  the  armature  stud.  Binding  posts  are  screwed  to  the 
synchronizing  frame  and  the  ends  of  the  magnet  coils  are 
fastened  thereto  with  metal  clips. 

The  blue  wires  in  the  clock  case  are  coiled  and  have  a 
metal  clip  soldered  to  them.*  They  connect  direct  by  these 
clips  to  the  binding  posts,  thus  making  a  firm  connection, 
and  are  not  liable  to  oxidize.  With  the  various  points  of 
adjustment  a  pair  of  magnets  burned  out  or  otherwise 
defective  may  readily  be  replaced  in  from  five  to  ten  min- 
utes. 

When  replacing  a  pair  of  synchronizing  magnets  pro- 
ceed as  follows :  Remove  the  old  pair  and  then  loosen  all 
four  screws  in  the  yoke,  pushing  it  up  against  the  tops 
of  the  oblong  holes,  then  tighten  down  lightly.  Fasten  the 
new  pair  of  magnets  to  the  yoke  with  the  inner  ends  of 
the  coils  showing  at  the  outside  of  the  movement.  Press 
the  armature  upward  until  the  synchronizing  lever  locks 
tightly  on  the  cannon  socket  and  the  heart-shaped  cams, 
then  loosen  the  magnet  yoke  screws  and  press  the  magnets 
down  on  the  spring  on  top  of  the  armature.  Then  tighten 
the  yoke  screws  on  the  front  plate  and  see  that  the  back 
of  the  magnets  clears  the  armature  by  one-hundredth  of 
an  inch  (the  thickness  of  a  watch  paper),  when  the  screws 
in  the  back  of  the  yoke  can  be  set  down  firmly.  The  ad- 
justment screw  may  then  be  turned  up  until  it  presses 
lightly  against  the  magnet  head.  When  current  is  passed 
through  the  magnets  and  held  there  the  armature  must 
clear  the  magnets  without  touching.  The  magnet  coils 
must  then  be  connected  to  their  respective  binding  posts  by 
slipping  the  metal  clips  soldered  to  them  under  the  rubber 
bushing,  making  a  metallic  connection  with  the  binding 
plates.  Fasten  these  screws  down  tight  to  insure  good 
connections. 


THE    MODERN    CLOCK, 


415 


The  Master  Clock. — Is  a  finely  finished  movement 
with  mercurial  pendulum  that  beats  seconds  and  a  Gerry 
gravity  escapement.  At  the  left  and  near  the  center  of  the 
movement  is  a  device  for  closing  the  synchronizing  circuit 


/O^ 


Fig.  U2 


once  each  hour.  The  device  consists  of  a  stud  on  which 
is  an  insulator  having  two  insulated  spring  fingers,  C  and 
D,  one  above  the  other,  as  shown  in  Fig.  142,  except  at 
the  points  where  they  are  cut  away  to  lie  side  by  side  on 
an  insulated  support.  On  these  fingers,  and  near  the 
insulator,  are  two  platinum  pieces,  E  and  F,  so  adjusted 


4l6  THE    MODERN    CLOCK. 

as  to  be  held  apart,  except  at  the  time  of  synchronizing. 

A  projection,  B,  from  the  insulator  rests  on  the  edge 
of -a  disc  on  the  center  arbor.  At  ten  seconds  before  the 
hour,  a  notch  in  this  disc  allows  the  spring  to  draw  the 
support  downward,  leaving  the  points  of  the  fingers,  C 
and  D,  resting  on  the  raised  part  of  the  rubber  cam  on 
the  escape  arbor.  The  end  of  the  finger,  C,  is  made 
shorter  than  that  of  D,  and  at  the  fifty-ninth  second,  C 
drops  and  closes  the  circuit  by  E  striking  F.  At  the 
next  beat  of  the  pendulum  the  long  finger  D  drops  and 
opens  the  circuit  again. 

The  winding  is  the  same  as  in  the  regular  self-winding 
clocks,  the  motor  wire  and  seconds  contact  being  con- 
nected to  the  binding  plates  at  the  left,  from  which 
brown  wires  lead  up  to  the  battery.  Two  wires  from  the 
synchronizing  device  are  connected  to  the  binding  plates 
at  the  left,  from  which  blue  wires  run  out  to  the  line. 

Before  connecting  the  clock  to  the  line  it  must  be  run 
until  it  is  well  regulated,  and  also  to  learn  if  the  con- 
tacts are  working  correctly.  Regulate  at  first  by  the 
nut  at  the  bottom  of  the  rod  until  it  runs  about  one 
second  slow  in  24  hours  (a  full  turn  of  the  nut  will 
change  the  rate  about  one-half  miniite  per  day).  The 
manufacturers  send  with  each  clock  a  set  of  auxiliary 
pendulum  weights,  the  largest  weighing  one  gram,  the 
next  in  size  five  decigrams  and  the  smallest  two  deci- 
grams; these  weights  are  to  make  the  fine  regulations  by 
placing  one  or  more  of  them  on  the  little  table  that  is 
fastened  about  the  middle  of  the  pendulum  rod.  The  five 
decigram  weight  will  make  the  clock  gain  about  one 
second  per  da}^,  and  the  other  weights  in  proportion. 
Care  must  be  taken  not  to  disturb  the  swing  of  the 
pendulum,  as  a  change  of  the  arc  changes  the  rate. 

To  start  the  clock  after  it  is  regulated,  stop  it,  with 
the  second  hand  on  the  fiftieth  second;  move  the  hands 
forward  to  the  hour  at  which  the  signal  comes  from  the 


THE    MODERN    CLOCK. 


^'7 


observatory;  then  press  the  minute  hand  back  gently  un- 
til it  is  stopped  by  the  extension  on  the  hour  contact, 
Fig.  142,  and  beat  the  clock  up  to  the  hour.  This  ensures 
the  hour  contact  being  in  position  to  send  the  synchronize 
ing  signal. 

A  good  way  to  start  it  with  observatory  time  is  with 
all  the  hands  pointing  to  the  "signal"  hour;  hold  the 
pendulum  to  one  side  and  when  the  signal  comes  let  it 
go.  With  a  little  practice  it  can  be  started  very  nearly 
correct. 

Clocks  not  lettered  in  the  bottom  of  the  case  must  be 
wound  before  starting  the  pendulum.  To  do  this  press 
the  switch  shown  in  Fig.  136,  which  is  on  the  left  side 
of  the   case  and   under  the   dial. 

Continue  the  pressure  until  the  winding  ceases.  Then 
set  the  hands  and  start  the  pendulum  in  the  usual  way. 
If  the  bell  is  not  wanted  to  ring,  bend  back  the  hammer. 

Secondary  Dials. — One  of  the  most  deceptive  branches 
of  clock  work  is  the  secondary  dial,  or  "minute  jumper." 
Ten  years  ago  it  was  the  rule  for  all  manufacturers  of  elec- 
tric clocks  to  put  out  one  or  more  patterns  of  secondary 
dials.  Theoretically  it  was  a  perfect  scheme,  as  the  sec- 
ondary dial  needed  no  train,  could  be  cheaply  installed  and 
could  be  operated  without  trouble  from  a  master  clock,  so 
that  all  dials  would  show  exactly  the  same  time.  Practical- 
ly, however,  it  proved  a  very  deceptive  arrangement.  The 
clocks  were  subject  to  two  classes  of  error.  One  was  that  it 
was  extremely  difficult  to  make  any  mechanical  arrangement 
in  which  the  hands  would  not  drive  too  far  or  slip  backward 
when  the  mechanism  was  released  to  advance  the  minute 
hand.  The  second  class  of  errors  arose  from  faulty  con- 
tacts at  the  master  clock  and  variation  in  either  quantity 
or  strength  of  current.  Another  and  probably  the  worst 
feature  was  that  all  such  classes  of  apparatus  record  their 
own  errors  and  thereby  themselves  provide  the  strongest 


4lS  THE    MODERN    CLOCK. 

evidence  for  condemnation  of  the  system.  Clocks  could  be 
wound  once  an  hour  with  one-sixtieth  of  the  chance  of  error 
of  those  wound  once  per  minute,  and  they  could  be  wound 
hourly  and  synchronized  daily  with  i-i440th  of  the  line 
troubles  of  a  minute  s}^stem. 

The  minute  jumpers  could  not  be  synchronized  without 
costing  as  much  to  build  and  install  as  an  ordinary  self- 
winding clock,  with  pendulum  and  time  train,  and  after  try- 
ing them  for  about  ten  years  nearly  all  the  companies  have 
substituted  self-winding  time  train  clocks  with  a  synchron- 
izing system.  They  have  apparently  concluded  that,  since 
it  seems  too  much  to  expect  of  time  apparatus  that  it  will 
work  perfectly  under  all  conditions,  the  next  thing  to  do  is 
to  make  the  individual  units  run  as  close  to  time  as  is  com- 
mercially practicable  and  then  correct  the  errors  of  those 
units  cheaply  and  quickly  from  a  central  point. 

It  is  for  these  reasons  that  the  secondary  dial  has  prac- 
tically disappeared  from  service,  although  it  was  at  one  time 
in  extensive  use  by  such  companies  as  the  Western  Union 
Telegraph  Company,  the  Postal  Telegraph  and  the  large 
buildings  in  which  extensive  clock  systems  have  been  in- 
stalled. 

Fig.  143  shows  one  form  of  secondary  dial  which  in- 
volves a  screw  and  a  worm  gear  on  the  center  arbor,  which, 
it  will  be  seen,  is  adapted  to  be  turned  through  one  minute 
intervals  without  the  center  arbor  ever  being  released  from 
its  mechanism.  This  worm  gear  was  described  in  the 
American  Jeweler  about  fifteen  years  ago,  when  patented 
by  the  Standard  Electric  Time  Company  in  connection  with 
their  motor-driven  tower  clocks,  and  modifications  of  it  have 
been  used  at  various  times  by  other  companies. 

The  worm  gear  and  screw  system  shown  in  Fig.  143  has 
the  further  advantage  that  it  is  suitable  for  large  dials,  as 
the  screw  may  be  run  in  a  box  of  oil  for  dials  above  four 
feet  and  for  tower  clocks  and  outside  work.  This  will  read- 
ily be  seen  to  be  an  important  advantage  in  the  case  of  large 


THE    MODERN    CLOCK. 


419 


hands  when  they  arc  loaded  with  snow  and  ice,  requiring- 
more  power  to  operate  them. 

All  secondaries  operate  by  means  of  an  electromagnet 
raising  a  weight,  the  weight  generally  forming  the  armature  ; 
the  fall  of  the  weight  then  operates  the  hands  by  gravity. 


Fig.143.    Minute  jumper.    A,  armature;  M,  magnets;  "W,  worm  gear  on 
center  arbor ;  B,  oil  box  for  worm ;  R,  four  toothed  ratchet. 


Direct  action  of  the  current  in  such  cases  is  impracticable, 
as  the  speed  of  starting  with  an  electric  current  would 
cause  the  machine  to  tear  itself  to  pieces. 

This  screw  gear  is  the  only  combination  known  to  us  that 
will  prevent  the  hands  from  slipping  or  driving  by  and  re- 
duces the  errors  of  the  secondary  system  to  those  of  one 
class,  namely,  imperfections  in  the  contact  of  the  master 
clock,  insufficient  quantity  or  strength  of  current,  or  acci- 
dental "crosses"  and  burnings. 

The  series  arrangement  of  wiring  secondaries  was  for- 
merly greatly  favored  by  all  of  the  manufacturers,  but  it 


420 


THE    MODERN    CLOCK. 


was  found  that  if  anything  happened  to  one  clock  it  stopped 
the  lot  of  them;  and  where  more  than  fifty  were  in  series, 
the  necessary  voltage  became  so  high  that  it  was  impractica- 
ble to  run  the  clocks  with  minute  contacts.  The  modern 
system,  therefore,  is  to  arrange  them  in  multiples,  very  much 
after  the  fashion  of  incandescent  lamps,  then  if  one  clock 
goes  wrong  the  others  are  not  affected.  Or  if  the  current 
is  insufficient  to  operate  all,  only  those  which  are  farthest 
away  would  go  out  of  time. 

Very  much  smaller  electromagnets  will  do  the  work  than 
are  generally  used  for  it,  and  the  economy  of  current  in 
such  cases  is  worth  looking  after,  as  with  sixty  contacts  per 
"hour  batteries  rapidly  play  out  if  the  current  used  is  at  all 
excessive.  Where  dry  batteries  are  used  on  secondaries 
care  should  be  taken  to  get  those  which  are  designed  for  gas 
engine  ignition  or  other  heavy  work.  Wet  batteries,  with 
the  zincs  well  amalgamated,  will  give  much  better  satisfac- 
tion as  a  rule  and  if  thp  plant  is  at  all  large  it  should  be  oper- 
ated from  storage  cells  with  an  engineer  to  look  after  the 
battery  and  keep  it  charged,  unless  current  can  be  taken 
from  a  continuously  charged  lighting  main.  This  can  be 
readily  done  in  such  instances  as  the  specifications  call  for  in 
the  new  custom  house  in  New  York,  namely,  one  master 
clock  and  i6o  secondary  dials. 

Electric  Chimes. — There  have  lately  come  into  the  mar- 
ket several  devices  for  obtaining  chimes  which  allow  the 
separation  of  the  chimes  and  the  timekeeping  apparatus, 
connection  being  made  by  means  of  electricity.  In  many 
respects  this  is  a  popular  device.  It  allows,  for  instance,  a 
full  set  of  powerful  tubular  chimes,  six  feet  or  more  in 
length,  to  be  placed  in  front  of  a  jewelry  store,  where  they 
offer  a  constant  advertisement,  not  only  of  the  store  itself, 
but  of  the  fact  that  chiming  clocks  may  be  obtained  there. 
It  also  allows  of  the  completion  by  striking  of  a  street  clock 
which  is  furnished  with  a  time  train  and  serves  at  once  as 


THE    MODE  KM    CLOCK. 


421 


timepiece  and  sign.  ]\lany  of  these  have  tubular  chimes  in 
which  the  hour  bell  is  six  feet  in  length  and  the  others  cor- 
respondingly smaller.  They  have  also  been  made  with  bells 
of  the  usual  shape,  which  are  grouped  on  posts,  or  hung  in 


Fig.  144.    Cbimes  of  beUs  in  rack. 


Fig.  145.    Chimes  of  bells  with  resonators. 


racks  and  operated  electrically.  It  may  also  be  used  as  a 
ship's  bell  outfit  by  making  a  few  minor  changes  in  the  con- 
troller. 

Fig.  144  shows  a  peal  of  bells  in  which  the  rack  is  thirty- 
six  inches  long  and  the  height  of  the  largest  bell  is  eight 
inches,  and  the  total  weight  thirty  pounds.  This,  as  will 
readily  be  seen,  can  be  placed  above  a  doorway  or  any  other 
convenient  position  for  operation ;  or  it  may  be  enclosed  in 
a  lattice  on  the  roof,  if  the  building  is  not  over  two  stories 
in  height.  The  lattice  work  will  protect  the  bells  from  the 
weather  and  at  the  same  time  let  out  the  sound. 

Fig.  145  shows  the  same  apparatus  with  resonators  at- 
tached. These  are  hollow  tubes  which  serve  as  sounding 
boards,  largely  increasing  the  sound  and  giving  the  effect 


422 


THE    MODERN    CLOCK. 


of  much  larger  bells.  Fig.  146  shows  a  tubular  chime  and 
the  electrical  connections  from  the  clock  to  the  controller 
and  to  the  hammers,  which  are  operated  by  electro-magnets, 
so  that  a  heavy  leaden  hammer  strikes  a  solid  blow  at  the 
tops  of  the  tubes. 


^.^^'i!=^:;^^^^^^^;x3^  ^^ 


THF.W.GR£ENELEaRlcCQ^ 

"IMPERIAL" 

WuTMINSTERflETRICCHIflETIIBB 


U 


rr"--"i 


u 


Hi 

I 

i 


CkECTKIC   J 
CONTROLLER 


0 


y?^^ 


Fig.  146,    Tubular  electric  chimes. 


The  dials  of  such  clocks  contain  electrical  connections  and 
the  minute  hand  carries  a  brush  at  its  outer  end.  The  con- 
tact is  shown  in  enlarged  view  in  Fig.  147,  by  which  it  will 
be  seen  that  the  metal  is  insulated  from  the  dial  by  means 
of  hard  rubber  or  other  insulating  material,  so  that  the 
brush  on  the  minute  hand  wall  drop  suddenly  and  firmly 
from  the  insulator  to  the  metallic  contact  when  the  minute 
hand  reaches  fifteen,  thirty,  forty-five  or  sixty  minutes. 
There  is  a  common  return  wire,  either  screwed  to  the  frame 
of  the  clock,  or  attached  to  the  dial,  which  serves  to  close 


THE    MODERN    CLOCK.  423 

the  various  circuits  and  to  give  four  strokes  of  the  chimes  at 
the  quarter,  eight  at  the  half,  twelve  at  the  three-quarter, 
and  sixteen  at  the  hour,  followed  by  the  hour  strike.     The" 
friction  on  the  center  arbor  is  of  course  adjusted  so  as  to 
carry  the  minute  hand  without  slipping  at  the  contacts. 

By  this  means  a  full  chime  clock  may  be  had  at  much  less 
cost  than  if  the  whole  apparatus  had  to  be  self-contained  and 
the  facilities  of  separation  between  the  chimes  and  the  time- 
keeping apparatus,  as  hinted  above,  gives  many  advantages. 


Fig.  147.    Enlarged  view  of  connections  on  dial. 

For  instance,  the  same  clock  and  controller  may  operate 
tubes  inside  the  room  and  bells  outside,  or  vice  versa.  These 
are  operated  by  wet  or  dry  batteries  purchased  at  local 
electrical  supply  houses,  and  the  wiring  is  done  with  plain 
covered  bell  wire,  or  they  may  be  operated  by  current  from 
a  lighting  circuit,  suitably  reduced,  if  the  current  is  con- 
stantly on  the  mains.  As  a  full  chime  with  sixteen  notes 
at  the  hour  strikes  more  than  a  thousand  times  a  day,  con- 
siderable care  should  be  taken  to  obtain  only  the  best  bat- 
teries where  these  are  used,  as  after  the  public  gets  used 
to  the  chimes  the  dealer  will  be  gre:itly  annoyed  by  the 
number  of  people  asking  for  them  if  they  are  stopped  tem- 
porarily. 

There  has  lately  developed  a  tendency  to  avoid  tlic  set 
tunes,  such  as  the  Westminster  and  the  Wliittington  chimes, 
and  to  sound  the  notes  as  complete  full  notes,  such  as  the 
first,  third  and  fifth  of  the  octave  for  the  first,  second  and 
third  quarters,   followed   by  the  hour   strike.     This   allows 


424  THE    MODERN    CLOCK. 

them  to  be  struck  in  any  order  and  for  a  smaller  chime  re- 
duces the  cost  considerably.  The  tubes  used  are  rolled  of 
bell  metal  and  vary  in  pitch  with  the  manufacture,-  so  that 
the  only  way  to  obtain  satisfactory  tones  is  to  cut  your  tubes 
a  little  long  and  then  tune  them  by  cutting  ofif  afterwards, 


/6  C/fimes  ar7c/y,^^f^^^^       ^^^^^^^^anJ  Connect/nn 
/}Oc/r  ^^^^^^/^^^^^\^     *^0    1  II  #^^>VA^;'^/W  around 

/^^\  All  /       ^^''     ^/^/ 


Fig.  148.    Connections  and  contacts  on  front  of  clock  dial. 

the  tone  depending  upon  the  thickness  of. the  wall'  of  the 
tube  and  its  length.  The  bells  are  tuned  by  turning  from 
the  rim  or  from  the  upper  portions  as  it  is  desired  to  raise 
or  lower  the  tone,  and  if  the  resonators  are  used  they  are 
tuned  in  unison  with  the  bells. 

Of  the  ordinary  bells,  Fig.  144,  the  dimensions  run: 
First,  height  four  inches,  diameter  ^Yi ;  second,  height  four 
inches,  diameter  5J4  inches ;  third,  height  4^  inches,  diam- 
eter 5^  inches;  fourth,  height  4j/^  inches,  diameter  5^ 
inches;  fifth,  height  4^  inches,  diameter  63^  inches.     For 


THE    MODERN    CLOCK. 


425 


the  tubes  the  approximate  length  is  six  feet  for  the  longest 
tube  and  the  total  weight  of  the  chimes  is  43  pounds. 
For  the  controller  the  size  is  nine  by  eleven  by  six  inches, 


I 


1 
I 


I         I        I         I 

®     ®     (9)     ^ 


■//7<su/ofed 

9- 


Fig.  149.    Connections  and  wiring  on  back  of  clock  dial. 


with  a  weight  of  ten  pounds.     The  hour  strike  may  be  had 
separately  from  the  chimes  if  desired. 

This  makes  an  easily  divisible  system  and  one  that  is  be- 
coming very  popular  with  retail  jewelers  and  to  some  ex- 
tent with  their  customers. 


CHAPTER   XXII. 

THE    CONSTRUCTION    AND    REPAIR    OF    DIALS. 

Probably  no  portion  of  the  clock  is  more  important  than 
the  dial  and  it  is  apparently  for  this  reason  that  we  find  so 
little  variation  in  the  marking.  The  public  refuses  to  ac- 
cept anything  in  the  way  of  ornamentation  which  interferes 
with  legibility  and  about  all  that  may  be  attempted  is  a  lit- 
tle flat  ornament  in  light  colors  which  will  not  obscure  the 
sight  of  the  hands,  as  it  is  in  reality  the  angle  made  by  the 
two  hands  which  is  read  instead  of  the  figures.  In  proof 
of  this  may  be  cited  the  many  advertising  dials  in  which 
one  letter  takes  the  place  of  each  character  upon  the  dial 
and  of  the  tower  clocks  in  which  the  hours  are  indicated 
merely  by  blackened  characters,  being  nothing  less  than  an 
oblong  blotch  on  the  dial.  Thousands  of  people  will  pass 
such  a  dial  without  ever  noticing  that  the  regular  charac- 
ters do  not  appear.  Various  attempts  have  been  made  to 
change  the  colors  and  the  sizes  and  shapes  of  the  characters 
but  comparatively  few  are  successful.  A  black  dial  with 
gold  characters  and  hands  is  generally  accepted,  or  a  cream 
dial  with  black  hands,  but  any  further  experiments  are 
dangerous  except  in  the  cases  of  tower  clocks,  which  may 
have  gold  hands  on  any  light  colored  dial,  or  a  glass  dial. 
In  all  such  cases  legibility  is  the  main  factor  nought  and 
the  bright  metal  is  far  plainer  for  hands  and  chapters  than 
anything  that  may  be  substituted  for  them. 

In  tower  clocks  the  rule  is  to  have  one  foot  of  diameter 
of  the  dial  for  every  ten  feet  of  height.  Thus  a  clock  situ- 
ated one  hundred  feet  above  the  ground  level  should  have  a 

4.6 


THE    MODERN    CLOCK.  427 

ten  foot  dial.  On  very  large  dials  this  rule  is  deviated  from 
a  little,  but  not  much.  All  dials,  except  those  of  tower 
clocks,  should  be  fastened  to  the  movement,  rather  than  to 
the  case.  This  is  particularly  true  where  a  seconds  hand, 
with  the  small  opening  for  the  seconds  hand  sleeve,  makes 
any  twisting  or  warping  of  the  case  and  consequent  shift- 
ing of  the  dial  liable  to  rub  the  dial  against  the  sleeve  at  the 
seconds  hand  and  thus  interfere  with  the  timekeeping. 

The  wTiter  has  in  mind  a  case  in  which  a  large  number 
of  fine  clocks  w^ere  installed  in  a  new  brick  and  stone  build- 
ing. They  were  finely  finished  and  no  sooner  had  they  been 
hung  on  the  damp  w^alls  than  the  cases  commenced  to  swell 
and  twist.  It  was  necessary  three  times  to  send  a  man  to 
move  the  dials  which  had  been  attached  to  these  clocks. 
As  there  were  about  thirty  clocks  it  will  be  seen  that  this 
was  expensive.  After  the  walls  had  dried  out  the  cases  be- 
gan to  go  back  to  the  positions  in  which  they  were  origin- 
ally, as  the  moisture  evaporated  from  the  cases,  and  the 
dials  had  consequently  to  be  moved  through  another  series. 
All  told  it  took  something  like  a  week's  work  for  one  man 
to  shift  these  dials  half  a  dozen  times  during  the  first  nine 
months  of  their  installation.  If  these  dials  had  been  fas- 
tened on  pillars  on  the  movements,  the  shrinking  and  swell- 
ing of  the  cases  would  not  have  afifected  them. 

It  is  for  this  reason  that  dials  are  invariably  fastened  on 
the  movements  of  all  high  class  clocks. 

The  characters  en  clock  dials  are  still  very  largely 
Roman,  the  numerals  being  known  as  chapters.  Attem.pts 
have  been  recently  made  to  substitute  Arabic  figures  and  in 
such  cases  the  Arabic  figures  remain  upright  throughout  the 
series,  while  the  chapters  invariably  point  the  foot  of  the 
Roman  numeral  toward  the  center  of  the  dial.  This  makes 
the  Roman  numerals  from  IIII  to  VIII  upside  down,  Vv^hile 
in  the  Arabic  numerals  this  inversion  dees  net  cccr.r. 

The  propcrtions  [^cneral-v  ca:ictio"cd  by  usage  have  been 
found,  after  measuring  clock  dials,  all  the  Vv^ay  from  two 


428  THE    MODERN    CLOCK. 

to  eighteen  inches,  and  may  be  given  in  the  following  terms : 
With  a  radius  of  26  mm.  the  minute  circle  is  i^  mm.  The 
margin  between  minute  circles  and  chapters  is  i  mm.  The 
chapters  are  8^  mm.  The  width  of  the  thick  stems  of  the 
letters  are  ^4  rnm.  The  width  of  an  X  is  4  mm.  and  the 
slanting  of  X's  and  V's  is  twenty  degrees  from  a  radius  of 
the  dial.  The  letters  should  be  proportioned  as  follows: 
The  breadth  of  an  Tand  a  space  should  equal  one-half  the 
breadth  of  an  X,  that  is,  if  the  X  is  one-half  inch  broad,  the 
I  will  be  three-sixteenths  inch  broad  and  the  space  between 
letters  one-sixteenth  inch,  thus  making  the  I  plus  one  space 
equal  to  one-quarter  inch  or  half  the  breadth  of  an  X.  The 
V's  should  be  the  same  breadth  as  the  X's.  After  the  let- 
ters have  been  laid  off  in  pencil,  outline  them  with  a  ruHng 
pen  and  fill  in  with  a  small  camel's  hair  brush,  using  gloss 
black  paint  thinned  to  the  proper  consistency  to  work  well 
in  the  ruling  pen.  Using  the  ruling  pen  to  outline  the  let- 
ters gives  sharp  straight  edges,  which  would  be  impossible 
with  a  brush  in  the  hands  of  an  inexperienced  person. 

For  tower  clocks  the  chapters  and  minutes  together  will 
take  up  one-third  of  the  radius  of  the  dial ;  the  figures  two- 
thirds  of  this,  or  two-ninths  of  the  radius,  and  the  minutes 
two-thirds  of  the  remaining  one-ninth  of  the  radius,  with 
every  fifth  minute  more  strongly  marked  than  the  rest. 

We  often  hear  stories  concerning  the  IIII  in  place  of  IV. 
The  story  usually  told  is  that  Louis  XIV  of  France  was  in- 
specting a  clock  made  for  him  by  a  celebrated  watchmaker 
of  that  day  and  remarked  that  the  IV  was  an  error.  It 
should  be  IIII.  There  was  no  disputing  the  King  and  so 
the  watchmaker  took  away  the  dial  and  had  the  IIII  en- 
graved in  place  of  IV,  and  that  it  has  thus  remained  in  de- 
fiance of  all  tradition. 

Mr.  A.  L.  Gordon,  of  the  Seth  Thomas  Clock  Co.,  has 
the  following  to  say  concerning  this  story  and  thus  fur- 
nishes the  only  plausible  explanation  we  have  ever  seen  for 


THE    MODERN    CLOCK.  429 

the  continuance  of  this  manifest  error  in  the  Roman  num- 
eral of  the  dial : 

"That  the  attempt  has  been  made  to  use  the  IV  for  the 
fourth  hour  on  clock  dials,  any  one  making  a  study  of  them 
may  observe.  The  dials  on  the  Big  Ben  clock  in  the  tower 
of  the  Parliament  buildings,  London,  which  may  be  said  to 
be  the  most  celebrated  clock  in  the  world,  have  the  IV 
mark,  and  the  dial  on  the  Herald  building  in  New  York 
City  also  has  it. 

"That  the  IIII  mark  has  come  to  stay  all  must  admit, 
and  if  so  there  must  be  a  good  and  sufficient  reason.  Art 
writers  tell  us  that  pictures  must  have  a  balance  in  the  plac- 
ing and  prominence  of  the  several  subjects.  Most  conven- 
tional forms  are  equally  balanced  about  a  center  line  or  a 
central  point.  Of  the  latter  class  the  well  known  trefoil  is 
a  common  example. 

"A  clock  or  watch  dial  with  Roman  numerals  has  three 
points  where  the  numerals  are  heavier,  at  the  IIII,  VIII 
and  XII.  Fortunately  these  heavier  numerals  come  at 
points  equally  spaced  about  the  center  of  the  dial  and  about 
a  center  line  perpendicular  to  the  dial.  Of  these  three  heavy 
numerals  the  lighter  of  them  comes  at  the  top  and  it  is 
especially  necessary  that  the  other  two,  which  are  placed  at 
opposite  points  in  relation  to  the  center  line,  should  be  bal- 
anced as  nearly  as  possible.  As  the  VIII  is  the  heavier 
and  cannot  be  changed,  the  balancing  figure  must  be  made 
to  correspond  as  nearly  as  possible,  and  if  marked  as  IV, 
it  will  not  do  so  nearly  as  effectively  as  if  the  usual  IIII  is 
used." 

It  is  comparatively  an  easy  matter  to  make  a  metal  dial 
either  of  zinc,  copper  or  brass,  by  laying  out  the  dial  as  in- 
dicated above  with  Roman  chapters  and  numerals,  after 
first  varnishing  the  metal  with  asphaltum.  This  may  be 
drawn  upon  with  needle  points  which  cut  through  the 
asphaltum  and  make  a  firmly  defined  line  on  the  metal.  It 
is  best  to  lay  out  your  dial  in  lead  pencil  and  then  take  a 


430  THE    MODERN    CLOCK. 

metal  straight  edge  and  a  needle  point  and  trace  through 
on  the  pencil  marks.  Mistakes  may  be  painted  out  with 
asphaltum,  so  that  the  job  becomes  easy.  After  this  has 
been  done  a  comparatively  dull  graver  may  be  used  to  cut 
or  scrape  away  the  asphaltum  wdiere  the  metal  is  to  be 
etched  and  then  the  plate  may  be  laid  in  a  tray,  a  solution 
of  chloride  of  iron  poured  on  and  rocking  the  tray  will 
rapidly  eat  away  the  metal,  forming  sunken  lines  wherever 
the  copper  or  brass  is"  not  protected  by  the  asphaltum.  This 
furnishes  a  rough  surface  on  the  etched  portions,  which  en- 
ables the  filling  to  stick  much  better  than  if  it  were  smooth. 
In  tracing  the  circles  a  pair  of  heavy,  stiff,  carpenters'  com- 
passes will  serve  where  the  watchmaker  has  not  a  lathe 
large  enough  to  swing  the  dial.  In  all  such  cases  it  is  best 
to  start  with  a  prick-punched  center,  tracing  the  minute 
circles  and  the  serifs  of  the  chapters  with  the  compasses  and 
then  do  your  further  division  and  marking  by  lead  pen- 
cil, followed  with  the  needle  and  then  by  the  acids.  It 
should  be  done  before  the  holes  are  bored  for  the  minute 
and  seconds  centers,  as  you  then  have  an  exact  center  to 
mark  from  and  can  go  back  to  it  many  times. 

This  will  be  necessary  in  'dividing  the  minute  or  seconds 
circle  by  hand  (without  an  index  on  the  lathe),  as  one  of 
the  tests  of  true  division  consists  in  having  all  marks  lined 
up  with  a  straight  edge  placed  across  the  center.  Thus  IX 
and  III  should  be  in  line  with  the  center;  VI  and  XII;  X 
and  IIII;  I  and  VII,  etc.  It  will  readily  be  seen  that  for 
such  purposes  of  reference  the  center  should  not  be  punched 
too  large. 

If  it  is  desirable  to  ornament  the  dial,  the  desired  orna- 
ment may  be  drawn  on  in  the  plain  surface  through  the 
asphaltum  and  etched  at  the  same  time  as  the  chapters  and 
degrees.  Or  chapters  and  ornament  may  be  drawn,  pierced 
with  a  saw,  engraved,  filed  up  and  backed  up  with  a  plain 
plate  of  another  color.  Gold  ornament  and  silver  back- 
ground looks  well. 


THE    MODKKN    CLOCK.  43I 

Practically  all  the  clocks  having  seconds  hands  carry  that 
hand  in  such  a  position  as  to  partially  obscure  the  XII, 
with  the  exception  of  watchmakers'  regulators,  and  these, 
if  they  have  separate  hour,  minute  and  seconds  circles,  are 
made  large  enough  to  occupy  the  space  between  the  center 
and  the  minute  circle,  placing  the  hour  circle  between  the 
center  and  the  thirtieth  minute ;  'the  seconds  between  the 
.center  and  the  sixtieth  minute.  The  reason  for  this  is  that 
in^the  watchmakers'  regulators  the  hours  are  almost  a  mat- 
ter of  indifference ;  minutes  are  reldom  referred  to ;  the  real 
coniparison  in  watch  regulation  comes  on  the  seconds  hand. 
For  this  reason  the  seconds  hand  is  made  as  large  as  pos- 
sible and  the  chapters  being  placed  on  the  hour  circle  by 
themselves,  the  seconds  circle  may  occupy  almost  the  en- 
tire distance  between  the  center  of  the  dial  and  the  minute 
circle.  They  are  placed  one  above  the  other  because  in 
regulators  the  tim.e  train  is  nearly  always  a  straight-line 
train,  which  brings  the  seconds  arbor  vertically  over  the 
center  arbor,  and  consequently  the  centers  of  the  dials  must 
be  placed  on  a  vertical  line. 

When  the  engraving  has  been  properly  done  on  a  flat 
dial  it  is  desirable  to  fill  it  with  black  in  order  to  make  it 
legible.  There  are  several  methods  by  which  this  may  be 
done.  The  most  durable  is  to  make  a  black  enamel  and  if 
it  is  a  valuable  clock  the  movement  is  generally  worth  a  fine 
dial.  The  following  formula  will  furnish  a  good  black 
enamel : 

Siliceous    sand 12  parts 

Calcined    borax 20  parts 

Glass    of    antimony 4  parts 

Saltpetre 1  part 

Chalk 2  parts 

Peroxide    of   Manganese 5]/2  parts 

Fine   Saxony  Cobalt 2  parts 

The  enamel  is  ground  into  coarse  particles  like  sand,  and 
the  incised  lines  filled  with  it,  after  which  the  brass  or  cop- 


432  THE    MODERN    CLOCK. 

per  plate  is  heated  red  hot  to  fuse  the  enamel.  Two  or 
three  firings  may  be  necessary  to  completely  fill  the  lines ; 
after  filling  they  arc  stoned  off  level  with  the  surface  of  the 
dial.  Jeweler's  enamel  may  be  purchased  of  material  deal- 
ers and  used  for  the  dials. 

Black  asphaltum  mixed  with  a  little  wax  or  pitch,  or  even 
watchmakers'  cement,  used  to  fasten  staffs  and  pinions 
into  a  lathe  for  turning,  is  also  used  on  these  dials  and  with 
a  sufiicient  proportion  of  wax  or  pitch  it  prevents  shrinking 
and  forms  a  very  satisfactory  dial  with  the  single  exception 
that  it  cannot  be  cleaned  with  benzine  or  hot  potash,  which 
will  dissolve  the  enamel.  Shoemakers'  heel  ball  is  also  used 
for  repair  jobs.  In  order  to  make  either  of  these  stick,  the 
brass  or  copper  plate  is  heated  up  so  as  to  "hiss"  as  will  a 
laundry  flat  iron  when  touched  with  a  wetted  finger,  and 
a  cement  stick  is  rubbed  over  the  letters  to  fill  them;  the 
excess  of  filling  can  be  scraped  off  with  an  ivory  scraper 
when  at  the  right  temperature — a  little  below  the  boiling 
point  of  water.  Such  filled  letters  can  be  lacquered  over  by 
going  very  quickly  over  the  work  so  as  not  to  dissolve  the 
shellac  in  the  cement. 

Another  way  is  to  fill  the  letters  with  black  lacquer.  For 
quick  repairs  this  is  probably  as  good  as  any.  Many  of  the 
old  grandfather  clocks  have  been  filled  in  with  a  putty  made 
with  copal  varnish  and  some  black  pigment.  All  putties 
shrink  in  drying  and  consequently  crack  and  finally  fall  out. 
The  wax  and  pitch  are  not  subject  to  these  disadvantages. 
If  the  plates  are  to  be  polished,  polishing  should  precede 
the  filling  in  of  the  letters,  else  the  work  may  have  to  be 
done  all  over  again.  Black  sealing  wax  and  alcohol  are  also 
used,  applied  as  a  paint  w^th  a  fine  brush. 

If  the  dial  is  to  be  silvered  or  gilt  the  blacking  should  be 
done  first,  and  if  to  be  electroplated  the  blacking  should  be 
what  is  known  as  the  "platers'  resist,"  which  is  composed 
chiefly  of  asphaltum  and  pitch  dissolved  in  turpentine.  It 
is  also  called  "stopping-off"  varnish,  and  has  large  use  in 


THE    MODERN    CLOCK.  433 

the  plating  establishments  to  prevent  deposition  of  metal 
where  it  is  not  desired. 

The  repairer  who  gets  many  grandfather  clocks  will 
often  find  that  it  is  necessary  to  repaint  the  dial,  generally 
because  of  a  too  vigorous  scrubbing,  or  because  of  crack-; 
or  scaling,  which  the  owner  may  dislike.  It  is  always  best, 
however,  to  be  cautious  in  such  matters,  as  many  people 
value  such  a  clock  chiefly  on  account  of  its  visible  evidences 
of  age  and  such  cracks  form  generally  a  large  proportion 
of  such  evidence.  Therefore  it  is  best  never  to  touch  an 
antique  dial  unless  the  owner  desires  it. 

Such  dials  are  usually  sheet-iron,  and  tolerably  smooth, 
so  the  metal  will  need  but  a  few  coats  of  paint  to  prepare  it. 
For  ground  coats,  take  good,  ordinary  white-lead  or  zinc 
white,  ground  with  oil,  and  if  it  has  much  oil  mixed  with  it 
pour  "it  off  and  add  spirits  of  turpentine  and  Japan  dryer — 
a  teaspoonful  of  dryer  for  every  half  pint  of  paint..  The 
test  for  the  paint  having  the  right  amount  of  oil  left  in  it  is, 
it  should  dry  without  any  gloss.  Rub  every  coat  you  apply 
with  fine  sand-paper,  after  it  is  perfectly  dry,  before  apply- 
ing the  next  coat  of  paint.  For  the  final  coat,  lay  the  dial 
flat  and  go  over  it  with  French  zinc-white.  This  coat  dries 
very  slow,  and  for  a  person  not  used  to  such  work,  is  hard 
to  manage.  The  next  best  (and  for  ordinary  clock  or  watch 
making  the  best)  for  the  last  pure  white  coat  is  to  take  a 
double  tube  of  Windsor  &  Newton's  Kremnitz  white, 
thinned  wath  a  little  turpentine.  Such  tubes  as  artists  use 
are  the  kind.  Apply  this  last  w^hite  coat  with  a  flat,  camel's 
hair  brush.  The  tube-white  should  have  turpentine  enough 
added  to  cause  it  to  flow  freely,  and  sink  flat  and  smooth 
after  the  brush.  The  letters  or  figures  should  be  painted 
with  ivory-black,  which  is  also  a  tube  color.  This  black  is 
mixed  with  a  little  Japan,  rubbing-varnish  and  turpentine, 
and  the  lettering  is  done  with  a  small,  sign  waiter's  pencil. 
Any  flowers  or  ornaments  are  painted  on  at  the  same  time ; 
and  after  they  are  dry  the  dial  should  be  varnished  with 


/|34  '^^^    MODERN    CLOCK. 

Mastic  or  Damar  varnish  or  white  shellac.     All  kinds  of 
coach  (Copal)   varnish  are  too  yellow. 

.  Painted  dials  on  zinc  will  blister  and  crack  off  if  sub- 
jected to  extremes  of  heat  and  cold,  unless  they  are  painted 
with  zinc  white  instead  of  lead  for  all  white  coats.  The  rea- 
son is  the  great  difference  in  expansion  between  lead  paint 
and  metallic  zinc.  This  case  is  similar  to  that  of  using  an 
iron  oxide  to  paint  iron  work  of  bridges,  ships,  etc.,  where 
other  oxides  will  chip  and  scale  off. 

The  metal  dials  on  these  old  clocks  were  silvered  by 
hand.  When  you  get  such  a  dial,  discolored  and  tarnished, 
it  can  be.  cleaned  in  cyanide  and  resilvered,  without  sending 
it  to  an  clectroplater,  by  the  following  formula : 

Dissolve  a  stick  of  nitrate  of  silver  in  half  a  pint  of  rain 
water;  add  two  or  three  tablespoonfuls  of  common  salt, 
which  will  at  once  precipitate  the  silver  in  the  form-  of  a 
thick,  white  curd,  called  chloride  of  silver.  Let  the  chloride 
settle  until  the  liquid  is  clear;  pour  off  the  water,  taking 
care  not  to  lose  any  chloride ;  add  more  water,  thoroughly 
stir  and  again  pour  off,  repeating  till  no  trace  of  salt  or  acid 
can  be  perceived  by  the  taste.  After  draining  off  the  water 
add  to  the  chloride  about  two  heaped  tablespoonfuls  each 
of  salt  and  cream  of  tartar,  and  mix  thoroughly  into  a  paste, 
which,  when  not  in  use,  must  not  be  exposed  to  the  light. 
To  silver  a  surface  of  engraved  brass,  wash  the  curface 
clean  with  a  stiff  brush  and  soap.  Heat  it  enough  to  melt 
black  sealing  wax,  which  rub  on  with  a  stick  of  wax  until 
the  engraving  is  entirely  filled,  care  being  taken  not  to  burn 
the  wax.  With  a  piece  of  flat  pumice-stone,  and  some  pul- 
verized pumice-stone  and  plenty  of  water,  grind  off  the 
wax  until  the  brass  is  exposed  in  every  part,  the  stoning 
being  constantly  in  one  direction.  Finish  by  laying  an  even 
and  straight  grain  across  the  brass  with  blue  or  water  of 
Ayr  stone.  Take  a  small  quantity  of  pulverized  pumice- 
stone  on  the  hand,  and  slightly  rub  in  the  same  direction, 
which  tends  to  make  en   even   rT:rain ;  the  hands  mmi  be 


THE    .MODERN    CLOCK.  435 

entirely  free  from  soap  or  grease.  Rinse  the  brass  thor- 
oughly, and  before  it  dries,  lay  it  on  a  clean  board,  and 
gently  rub  the  surface  with  fine  salt,  using  a  small  wad  of 
clean  muslin.  When  the  surface  is  thoroughly  covered  with 
salt,  put  upon  the  wad  of  cloth,  done  up  with  a  smooth  sur- 
face, a  sufficient  quantity  of  the  paste,  say  to  a  dial  three 
inches  in  diameter  a  piece  of  tlie  size  of  a  marble,  wdiich 
rub  evenly  and  quickly  over  the  entire  surface.  The  brass 
will  assume  a  greyish,  streaked  appearance ;  add  quickly  to 
the  cloth  cream  of  tartar  moistened  with  water  into  a  thin 
paste ;  continue  rubbing  until  all  is  evenly  whitened.  Rinse 
quickly  under  a  copious  stream  of  water ;  and  in  order  to 
dry  it  rapidly,  dip  into  water  as  hot  as  can  be  borne  by  the 
hands,  and  when  heated,  holding  the  brass  by  the  edges, 
shake  off  as  much  of  the  water  as  possible,  and  rem.ove  any 
remaining  drops  with  clean,  dry  cloth.  The  bra^s  should 
then  be  heated  gently  over  an  alcohol  lamp,  until  the  wax 
glistens  without  melting,  when  it  may  be  covered  with  a 
thin  coat  of  spirit  varnish,  laid  on  with  a  broad  camel's 
hair  brush.  The  varnish  or  lacquer  must  be  quite  light- 
colored — diluted  to  a  pale  straw  color. 

It  is  now  possible  to  buy  silver  plating  solutions  which 
can  be  used  without  battery  and  they  will  produce  the  same 
effect  as  the  formula  just  given.  If  they  happen  to  be  in 
stock  for  the  repairing  of  jewelry  they  may  be  used  in 
cleaning  the  dials,  but  as  this  is  liable  to  fall  into  the  hands 
of  many  wdio  are  far  from  such  conveniences,  we  furnish 
the  original  recipe,  which  can  be  executed  anywhere  the 
materials  can  be  obtained. 

If  the  dial  is  of  brass,  very  good  effects  have  been  pro- 
duced by  stopping  off  portions  of  the  dial  in  an  ornamental 
pattern  before  silvering,  and  then  lacquering  after  removing 
the  resist.  But  for  a  plain  black  and  brass  dial  a  dip  of 
strong  sulphuric  acid  two  parts,  red  fuming  nitrous  acid 
one  part,  and  water  one  part,  mixed  in  the  open  air  and 
dipped  or  flowed  over  the  dial,  forms  what  is  known  as  the 


436  THE    MODERN    CI-OCK. 

platers'  bright  dip.  After  dipping  the  article  should  at  once 
be  rinsed  in  hot  water  and  dried,  and  lacquered  at  once  with 
a'  lacquer  of  light  gold  color.  This  makes  a  very  neat  and 
durable  finish. 

The  satin  effect  may  be  obtained  on  a  dial  by  prolonging 
the  acid  dip  and  otherwise  proceeding  as  before.  Many  of 
these  dials  were  of  zinc  and  all  that  applies  to  brass  or  cop- 
per may  be  also  executed  in  zinc,  but  in  plating  it  will  be 
found  necessary  to  plate  two  or  three  times,  as  the  single 
coating  will  apparently  disappear  into  the  zinc  unless  it  is 
given  a  heavy  deposit  of  copper  in  a  plating  bath.  Where 
it  is  desired  to  obtain  a  bright  gold  color,  the  gold  plating 
solutions  now  sold  for  the  coloring  of  jewelry  may  also  be 
used  on  either  of  these  metals.  For  the  reasons  given 
above,  however,  they  are  not  very  successful  on  a  zinc 
base. 

Many  of  the  cheap  clocks  have  paper  dials  glued  on  a 
zinc  plate  and  when  the  dial  is  soiled  the  repairer  cleans 
them  up  by  pasting  another  dial  on  top  of  the  original. 
These  dials  are  made  on  what  is  known  as  lithographic  label 
paper:  that  is  paper  which  is  waterproof  on  one  side,  so 
that  it  will  not  shrink  or  swell  when  dampened.  In  addition 
to  the  lithograph  coating  they  are  generally  given  a  varnish 
of  celluloid  by  the  clock  manufacturers,  thus  making  them 
practically  waterproof.  They  are  very  cheap  and  the  re- 
pairer will  find  that  he  will  obtain  in  prestige  from  such 
new  dials  far  more  than  they  cost. 

Tarnished  metal  dials  are  best  cleaned  by  a  dip  of  cyanide 
of  potassium,  of  about  the  same  strength  as  that  used  for 
cleaning  silver.  If  the  tarnished  parts  have  been  gilded, 
however,  the  cyanide  should  be  excessively  weak.  Mining 
men  use  a  cyanide  solution  for  the  recovery  of  gold,  which 
is  only  two-tenths  of  one  per  cent  cyanide,  and  this  will 
collect  all  the  gold  from  ore  that  runs  from  $10  to  $15  to 
the  ton,  the  pulp  in  such  cases  being  left  in  the  solution 
from  seventy  to  ninety  hours.     The  ordinary  cyanide  dip 


THE    MODERN    CLOCK.  437 

for  the  jeweler  is  one  ounce  to  thirty-two  of  water,  while 
the  miner's  solution  is  two-tenths  of  an  ounce  to  one  hun- 
dred ounces  of  water.  You  can  see  that  with  the  strong 
cyanide  solution  the  gilt  surface  will  all  be  taken  off  unless 
very  rapid  dipping  is  strictly  followed  by  thorough  wash- 
ing. 

A  novelty  which  keeps  periodically  coming  to  the  front, 
say  about  once  every  ten  years,  is  the  luminous  dial.  This 
is  done  by  painting  the  dial  with  phosphorus  or  a  phos- 
phorescent powder.  Then  when  it  is  placed  in  the  light  it 
will  absorb  light  and  give  it  off  in  the  dark  until  the  evap- 
oration of  the  phosphorus. 

The  composition  and  manufacture  of  this  phosphores- 
cent powder  is  effected  in  the  following  manner:  Take 
100  parts  by  weight  of  carbonate  of  lime  and  phosphate 
of  lime,  produced  by  calcination  of  sea-shells,  especially 
those  of  the  tridacna  and  cuttlefish  bone,  and  lOO  parts  by 
weight  of  lime,  rendered  chemically  pure  by  calcination. 
These  ingredients  are  well  miixed  together,  after  which  25 
parts  of  calcinated  sea  salt  are  added  thereto,  sulphur  being 
afterward  incorporated  therewith  to  the  extent  of  from  25 
to  50  per  cent  of  the  entire  mass,  and  a  coloring  matter  is 
applied  to  the  composition,  which  coloring  matter  consists 
of  from  3  to  7  per  cent  of  the  entire  mass  of  a  pow^der  com- 
posed of  a  mono-sulphide  of  calcium,  barium,  strontium, 
magnesium  or  other  substance  which  has  the  property  of 
becoming  luminous  in  the  dark,  after  having  been  impreg- 
nated with  light.  After  these  ingredients  are  well  mixed, 
the  composition  is  ready  for  use.  Its  application  to  clock 
dials  is  made  either  by  incorporating  suitable  varnish  there- 
with, such  as  copal,  and  applying  the  mixture  with  a  brush 
to  the  surface  of  the  dial,  or  by  the  production  of  a  dial 
which  has  a  self-luminous  property,  imparted  to  it  during 
its  manufacture.  This  is  effected  in  the  following  manner : 
From  5  to  20  per  cent  of  the  composition  obtained  and 
formed  as  above  described,  is  incorporated  with  the  glass 


438  THE    MODERN    CLOCK. 

while  it  is  in  a  fused  state,  after  which  the  glass  so  pre- 
pared is  molded  or  blown  into  the  shape  or  article  required. 
Another  process  consists  of  sprinkling  a  quantity  of  the 
composition  over  the  glass  article  while  hot,  and  in  a  semi- 
plastic  state,  by  either  of  which  processes  a  self-luminous 
property  will  be  imparted  to  the  article  so  treated. 

Where  enamel  dials  are  chipped  the  cracks  may  be  hidden 
by  first  pressing  the  cracks  very  slightly  open  and  washing 
out.  Then  work  in  a  colorless  cement  to  fill  the  crack,  allow 
to  dry  and  stone  down.  Where  holes  have  been  left  by  the 
chipping,  melt  equal  parts  of  scraped  pure  white  wax  and 
zinc  white  and  let  it  cool.  Warm  the  dial  slightly  and  press 
the  cold  wax  into  the  defective  places  and  scrape  off  with  a 
sharp  knife  and  it  will  leave  a  white  and  lustrous  surface. 
If  too  hard  add  wax ;  if  too  soft  add  some  zinc  white. 

Varnish  for  Dials,  Etc. — A  handsome  varnish  for  the 
dials  of  clocks,  watches,  etc.,  may  be  prepared  by  dissolving 
bleached  shellac  in  the  purest  and  best  alcohol.  It  offers 
the  same  resistance  to  atmospheric  influence  that  common 
shellac  does.  In  selecting  bleached  shellac  for  this  purpose 
be  careful  to  get  that  which  will  dissolve  in  alcohol,  as  some 
of  it  being  bleached  with  strong  alkalies,  is  thereby  rendered 
insoluble  in  alcohol.  The  shellac  when  dissolved  should 
be  of  a  clear  light  amber  color  in  the  bottle  and  this  will  be 
invisible  on  white  paper  when  dry. 

Colorless  celluloid  lacquer,  known  to  jewelers  as  "silver 
lacquer"  on  account  of  its  being  used  to  prevent  tarnish  on 
finished  hollow  ware,  also  makes  a  good  varnish  to  apply 
to  dials,  either  metallic  or  painted.  It  is  best  to  have  it 
thin,  flow  it  on  the  dial  and  then  level  the  dial  to  dry. 

Success  in  the  repairing  of  a  broken  enameled  clock  dial 
will  greatly  depend  upon  the  practical  skill  of  the  operator, 
as  well  as  of  a  knowledge  of  the  process.  If  it  is  only  de- 
sired to  repair  a  chipped  place  on  a  dial,  a  fusible  enamel  of 
the  right  tint  should  be  procured  from  a  dealer  in  watch- 


THE    MODERN    CEOCK.  439 

makers'  materials,  which,  with  ordinary  care,  may  be  fused 
on  the  chipped  place  on  the  dial  so  as  to  give  it  a  workman- 
like appearance  when  finished  off.  The  place  to  receive  the 
enamel  should  be  well  cleaned,  and  the  moist  enamel  spread 
over  the  place  in  a  thin,  even  layer;  and,  after  allowing  it 
to  dry,  the  dial  may  be  held  over  a  spirit  lamp  until  the  new 
enamel  begins  to  fuse,  when  it  may  be  smoothed  down  with 
a  knife.  The  dial,  after  this  operation,  is  left  to  cool,  when 
any  excess  of  enamel  may  be  removed  by  means  of  a  corun- 
dum file,  and  subsequently  polished  with  putty  powder 
(oxide  of  tin).  The  ingredients  of  enamel,  after  being 
fused  into  a  mass,  are  allowed  to  cool,  then  crushed  to 
powder  and  well  washed  to  get  rid  of  inpurities,  and  the  re- 
sulting fine  powder  forms  the  raw  material  for  enameling. 
It  is  applied  to  the  object  to  be  enameled  in  a  plastic  con- 
dition, and  is  reduced  to  enamel  by  the  aid  of  heat,  being 
.first  thoroughly  dried  by  gentle  heat,  and  then  fused  by  a 
stronger  one.  The  following  is  a  good  white  enamel  for 
dials : 

Silver  sand,  3  ounces ;  red  lead,  3^  ounces ;  oxide  of  tin, 
2.y2  ounces ;  saltpeter,  ^  ounce ;  borax,  2  ounces,  flint  glass, 
I  ounce ;  manganese  peroxide,  2  grains.  The  basis  of  nearly 
all  enamels  is  an  easily  fusible  colorless  glass,  to  which  the 
required  opacity  and  tints  are  given  by  the  addition  of  var- 
ious metallic  oxides,  and  these,  on  being  fused  together, 
form  the  different  kinds  of  vitreous  substances  used  by 
enamel  workers  as  the  raw  material  in  the  art  of  enameling. 

The  hands  of  timekeepers  are  worthy  of  more  attention 
than  is  frequently  bestowed  upon  them  by  watch  and  clock- 
makers.  Their  shape  and  general  arrangement,  and  the 
neatness  of  their  execution  is  often  taken  by  the  general 
public  as  an  index  to  the  character  of  the  entire  mechanism 
that  moves  them;  and  some  are  apt  to  suppose  that  when 
care  is  not  bestowed  on  the  parts  of  the  time-piece  which 
are  most  seen,  much  care  cannot  be  expected  to  have  been 
exercised  on  the  parts  of  the  watch  or  clock  which  are  in- 


440  THE    MODERN    CLOCK. 

visible  to  the  general  view.  Although  we  are  not  prepared 
to  fully  endorse  the  opinion  that  when  the  hands  of  time- 
pieces are  imperfect  in  their  execution,  or  in  their  general 
arrangem.ent,  all  the  mechanism  must  of  necessity  be  im- 
perfect also;  still  we  think  that  in  many  instances  there  is 
room  for  improving  the  hands  of  timepieces,  and  we  desire 
to  direct  more  attention  to  this  subject  by  the  workmen. 

In  the  general  arrangement  of  the  hands  of  watches  and 
clocks,  distinctness  of  observation  should  be  the  great  point 
aimed  at,  and  everything  that  has  a  tendency  to  lead  to  con- 
fusion should  be  carefully  avoided.  Clocks  that  have  a 
number  of  hands  radiating  from  one  center,  and  moving 
round  one  circle — as  for  instance,  center  seconds,  days  of 
the  month,  equation  of  time,  alarms  and  hands  for  other 
purposes — may  show  a  good  deal  of  mechanical  skill  on  the 
part  of  the  designer  and  maker  of  the  timepiece ;  but  so 
many  hands  moving  together  around  one  circle,  although 
they  may  be  of  different  colors,  causes  confusion,  and  re- 
quires considerable  effort  to  make  out  what  the  different 
hands  point  to  in  a  dim  light,  and  this  confusion  is  fre- 
quently increased  by  the  necessity  for  a  counterpoise  being 
attached  to  some  of  the  hands.  As  a  rule  timekeepers  should 
be  so  arranged  that  never  more  than  the  hour  and  minute 
hand  should  move  from  one  center  on  the  dial.  There  may 
be  special  occasions  when  it  is  necessary  or  convenient  to 
have  center  seconds  to  large  dials ;  but  these  occasions  are 
rare,  and  we  are  talking  about  the  hands  of  timekeepers 
in  every-day  use  for  the  ordinary  purposes  of  life,  and  also 
for  scientific  uses.  In  astronomical  clocks  and  watchmakers' 
regulators  we  find  the  hour,  minute  and  second  hands  mov- 
ing on  separate  circles  on  the  same  dial ;  and  the  chief  rea- 
son for  this  arrangement  is  to  prevent  mistakes  in  reading 
the  time.  In  chronometers,  especially  those  measuring-  side- 
real time,  the  hour  hand  is  frequently  suppressed,  and  the 
hours  are  indicated  by  a  star  wheel,  or  ring,  with  figures 
engraved  on  it,  that  show  through  a  hole  in  the  dial. 


THE     MODE  UN     CLOCK. 


^41 


Hour  and  minute  hands  should  be  shaped  so  that  the  one 
can  be  easily  distinguished  from  the  other  without  any  ef- 
fort on  the  part  of  the  observer.  Probably  a  straight  minute 
hand,  a  little  swelled  near  the  point,  and  a  spade  hour  hand, 
are  the  shapes  best  adapted  for  this  purpose,  especially  if 
the  hands  have  to  be  looked  at  from  a  distance.  There  are 
occasions,  however,  when  a  spade  hand  cannot  be  used  with 
propriety.  In  small  watches  and  .clocks  having  ornamental 
cases,  hands  of  other  designs  are  desirable,  but  whatever 
be  the  pattern  used,  or  whatever  color  the  hands  m.ay  be 
made,  it  should  ever  be  remembered  that  wdiile  a  design  in 
harmony  with  the  case  is  perfectly  admissible,  the  sole  use 
of  hands  is  to  mark  the  time  distinctly  and  readily. 

The  difference  in  the  length  of  the  hour  and  minute  hands 
is  also  an  important  point  in  rendering  the  one  easily  dis- 
tinguished from  the  other.  The  extreme  point  of  the  hour 
hand  should  extend  so  as  to  just  cover  the  edge  of  the  in- 
side end  of  the  numerals  and  the  extreme  point  of  the 
minute  hand  should  cover  about  two-thirds  of  the  length  of 
the  minute  divisions.  Hands  made  of  this  length  will  be 
found  to  mark  the  hours  and  minutes  with  great  plainness, 
and  the  rule  will  be  found  to  work  well  in  dials  of  all  sizes. 
As  a  general  rule,  the  extreme  points  of  the  hands  should 
be  narrow.  The  point  of  the  hour  hand  should  never  be 
broader  than  the  thickest  stroke  of  any  of  the  numerals, 
and  the  extreme  point  of  the  minute  hand  never  broader 
than  the  breadth  of  the  minute  lines ;  and  in  small  work  it  is 
well  to  file  the  ends  of  the  hands  to  a  fine  point.  The  ends 
of  minute  hands  should  in  every  instance  be  bent  into  a 
short,  graceful  curve  pointing  toward  the  dial,  and  as  close 
to  it  as  will  just  allow  the  point  of  the  hand  to  be  free.  The 
minute  hands  of  marine  chronometers  are  invariably  bent 
in  this  manner,  and  the  hands  of  these  instruments  are 
usually  models  of  neatness  and  distinctness. 

Balancing  hands  by  means  of  a  counterpoise  is  a  subject 
which  requires  some  attention  in  order  to  effect  the  perfect 


442  THE    MODERN    CLOCK. 

poise  of  the  hand  without  detracting  anything  from  its  dis- 
tinctness. In  watch  work,  and  even  in  ordinary  clock-  work, 
it  seldom  happens  that  any  of  the  hands  except  the  seconds 
require  to  be  balanced,  and  then  there  is  only  one  hand  mov- 
ing round  the  same  circle,  as  is  the  case  with  seconds  hands 
in  general.  We  have  become  so  accustomed  to  looking  at 
seconds  hands  with  projecting  tails  that  we  are  apt  to  re- 
gard the  appearance  of  the  hands  to  be  incomplete  without 
the  usual  tail ;  but  we  must  remember  that  the  primary  ob- 
ject in  view  in  having  a  tail  to  a  seconds  hand  is  to  counter- 
poise it,  not  to  improve  the  looks  of  the  hand  itself.  Poising 
becomes  an  actual  necessity  for  a  hand  placed  on  so  sensi- 
tive a  part  as  the  fourth  wheel  of  a  watch,  or  on  the  scape 
wheel  of  a  fine  clock.  When  only  one  hand  moves  in  the 
same  circle,  like  a  seconds  hand,  the  counterpoise  may  be 
effected  by  means  of  a  projecting  tail  without  in  any  way 
detracting  from  a  distant  reading  of  the  hands,  providing 
the  tail  is  not  made  too  long,  and  it  is  made  of  such  a  pat- 
tern that  the  one  end  can  easily  be  distinguished  from  the 
other.  In  minute  and  hour  hands,  however,  it  is  different. 
These  two  hands  move  round  the  same  circle,  and  a  coun- 
terpoise on  the  minute  hand  is  liable  at  a  distance  to  be  mis- 
taken for  the  hour  hand. 

The  minute  hands  of  large  timepieces  frequently  require 
to  be  balanced,  especially  if  the  dial  be  large  in  comparison 
to  the  size  of  the  movement;  and  in  very  large  or  tower 
clocks,  whatever  may  be  the  size  of  the  movement,  it  be- 
comes an  absolute  necessity  to  balance  the  hands.  In  our 
opinion,  tails  should  never  be  made  on  minute  hands,  when 
they  can  be  avoided,  and  in  cases  where  tails  cannot  be  dis- 
pensed with,  they  should  invariably  be  colored  the  same  as 
the  ground  of  the  dial.  In  almost  every  instance,  however, 
minute  hands  may  be  balanced  in  the  inside,  as  is  usual  with 
tower  clocks.  A  great  many  clocks  used  for  railway  and 
similar  purposes  in  Europe  have  their  minute  hands  bal- 
anced in  this  manner,  and  the  plan  works  admirably ;  for  in 


THE    MODERN    CLOCK. 


443 


Fig.  150.  Showing  counterpoise  on  arbor  of  minute  hand  in  tower  clock. 


444  THE    MODERN    CLOCK. 

addition  to  rendering  the  hands  more  distinct,  the  clocks  re- 
quire less  power  to  keep  them  going  than  when  the  hands 
are  balanced  from  the  outside. 

Tower  clock  hands  are  generally  made  of  copper,  elliptical 
in  section,  being  made  up  of  two  circular  segments  brazed 
together  at  the  edges,  with  internal  diaphragms  to  stiffen 
them.  The  minute  hand  is  straight  and  perfectly  plain,  with 
a  blunt  point.  At  the  center  of  the  dial  the  width  of  the 
minute  hand  is  one-thirteenth  of  its  length,  tapering  to 
about  half  as  much  at  the  point. 

The  hour  hand  is  about  the  same  width,  ending  jus|:  short 
of  the  dial  figure  and  terminating  in  a  palm  or  ornament. 
The  external  counterpoises  are  one-third  the  length  of  the 
minute  hand,  and  of  such  a  shape  that  they  will  not  be  con- 
founded with  either  of  the  hands ;  a  cylinder,  painted  the 
same  color  as  the  dial,  and  loaded  with  lead,  makes  a  good 
counterpoise.  This  counterpoise  may  be  partly  on  the  in- 
side of  the  dial  if  it  is  desired  to  keep  it  invisible,  but  it 
should  not  be  omitted,  as  it  saves  a  good  deal  of  power,  pre- 
vents the  twisting  of  the  arbors,  and  also  assists  in  over- 
coming the  action  of  the  wind  on  the  hands.  Two-thirds 
of  the  counterpoise  weight  may  be  inside,  as  shown  in  Fig. 
150. 

To  Blue  a  Clock  Hand  or  a  Spring. — To  blue  a  piece 
of  steel  that  is  of  some  length,  a  clock  hand  for  example, 
clockmakers  place  it  either  on  ignited  charcoal,  with  a  hole 
in  the  center  for  the  socket,  and  whitened  over  its  surface, 
as  this  indicates  a  degree  of  heat  that  is  approximately  uni- 
form, or  on  a  curved  bluing  tray  perforated  with  holes 
large  enough  to  admit  the  socket.  The  center  will  become 
violet  or  blue  sooner  than  the  rest,  and  as  soon  as  it  assumes 
the  requisite  tint,  the  hand  must  be  removed,  holding  it  with 
tweezers  by  the  socket,  or  by  the  aid  of  a  large  sized  arbor 
passed  through  it ;  the  lower  side  of  the  hand  is  then  placed 
on  the  edge  of  the  charcoal  or  bluing  tray,  and  removed  by 


THE    MODERN    CLOCK.  445 

gradually  sliding  it  off  toward  the  point,  more  or  less  slowly, 
according  to  the  progress  made  with  the  coloring;  with  a 
little  practice,  the  workman  will  soon  be  enabled  to  secure 
a  uniform  blue  throughout  the  length  and  even,  if  necessary, 
to  retouch  parts  that  have  not  assumed  a  sufficiently  deep 
tint. 

Instead  of  a  bluing  tray,  a  small  mass  of  iron,  with  a 
slightly  rounded  surface  and  heated  to  a  suitable  tempera- 
ture, can  be  employed ;  but  the  color  must  not  form  too 
rapidly,  and  this  is  liable  to  occur  if  the  temperature  of  the 
mass  is  excessive.  Nor  should  this  temperature  be  unevenly 
distributed. 

A  spring,  after  being  whitened,  can  be  blued  in  the  same 
way.  Having  fixed  one  end,  it  is  stretched  by  a  weight  at- 
tached to  the  other  end^  and  the  hot  iron  is  then  passed 
along  it  at  such  a  speed  that  a  uniform  color  is  secured.  Of 
course,  the  hot  iron  might  be  fixed  and  the  spring  passed 
over  it.  A  lamp  may  be  used,  but  its  employment  involves 
more  attention  and  dexterity. 


CHAPTER  XXIII. 

CLOCK  CASING  AND   CASE  REPAIRS. 

Precision  Clock  Cases. — The  casing  of  a  precision 
clock  is  uiily  secondary  in  importance  to  the  comoensation 
of  its  pendulum.  The  best  construction  of  an  efficient  case 
can  be  ascertained  only  by  most  careful  study  of  the  con- 
ditions under  which  the  clock  is  expected  to  be  a  standard 
timekeeper,  and  often  the  entire  high  accuracy  sought  by  re- 
fined construction  is  sacrificed  by  an  inefficient  case  and 
mounting. 

The  objects  of  casing  a  precision  clock  are  as  follows 

a.  To  protect  the  mechanism  from  the  effects  of  dust 
and  dirt, 

b.  To  avoid  changes  of  temperature  and  barometric 
pressure. 

c.  To  provide  an  enclosed  space  in  which  the  gas  me- 
dium in  which  the  pendulum  swings  shall  have  any  chem- 
ical constitution,  of  any  hygroscopic  condition. 

d.  There  must  be  provided  ready  means  of  seeing  and 
changing  the  condition  of  the  pendulum,  electric  apparatus, 
movement,  etc.,  without  disturbing  the  case  except  locally. 

Now  if  we  hold  the  above  considerations  in  view  we  can 
readily  see  that  cast  iron,  wood  and  glass,  with  joints  of 
wash  leather  (which  is  kept  soft  by  a  wax  cement  which 
does  not  become  rancid  with  age),  are  the  preferable  ma- 
terials. 

The  advantages  of  using  cast  iron  for  the  pillar  or  body 
of  the  case  are  that  it  can  b'e  cast  in  such  a  shape  as  to  re- 
quire very  little  finishing  afterwards,  and  that  only  such 
as  planing  parallel  surfaces  in  iron  planing  machines.     It 

446 


THE    MODKI^N    CLOCK:. 


447 


makes  a  stiff  column  for  mounting  the  pendulum  when  it 
rests  upon  a  masonry  foundation  from  below.  Plates  of 
glass  can  be  clamped  against  the  planed  surfaces  of  iron 
piers  (by  putting  waxed  wash  leather  between  the  glass  and 
the  iron)  so  as  to  make  air-tight  joints  without  difficulty. 

The  mass'  of  iron  symmetrically  surrounding  the  steel 
pendulum  is  the  safest  protection  the  clock  can  have  against 
casual  magnetic  disturbances.  In  the  language  of  elec- 
tricians it  ''shields"  the  pendulum^. 

Suppose,  then,  we  adopt  as  the  first  type  of  precision 
clock  case  which  our  present  knowledge  suggests,  that  of  an 
Iron  cylinder  or  rectangular  box  resting  on  a  m.asonry  pier, 
and  which  has  a  table  top  to  which  the  massive  pendulum 
bracket  is  firmly  bolted.  This  type  admits  of  the  weights 
being  dropped  in  small  cylinders  outside  of  the  cast  iron 
cylinder  or  box.  These  weight  cylinders,  of  course,  end  In 
the  table  top  of  the  clock  case  above  and  in  the  projecting 
base  of  the  flange  of  the  clock  case  below. 

With  this  construction  it  is  a  simple  matter  to  cover  the 
movement  with  a  glass  case,  preferably  made  rectangular, 
with  glass  sides,  ends  and  top,  with  rtietal  cemented  joints. 
The  metal  bottom,  edges  of  this  rectangular  box  can  be 
ground  to  fit  the  plane  surface  of  the  top  of  the  clock  case. 
Then,  by  covering  the  bottom  edges  with  such  a  wax  as  was 
used  in  making  the  glass  plates  fit  the  iron  case  in  front  or 
back,  we  can  secure  an  air-tight  joint  at  the  junction  of  the 
rectangular  top  glass  case  wath  iron  case.  In  practice  the 
W2LX  to  be  used  may  be  made  by  melting  together  and  stir- 
ring equal  parts  of  vaseline  and  beeswax.  The  proportions 
may  be  varied  to  give  a  different  consistency  of  wax,  and  It 
may  be  painted  on  with  a  brush  after  warming  over  a  small 
flame. 

If  the  clock  case  will  be  exposed  to  a  comparatively  high 
temperature,  say  95°  F.,  then  the  beeswax  can  be  3  parts  to 
I  of  vaseline.  The  good  quality  of  this  cement  wax  Is  that 
it  does  not  change  with  age,  or  at  least  for  several  years. 


448  THE    MODERN    CLOCK. 

is  very  clean,  and  can  be  wiped  off  completely  with  kerosene, 
or  turpentine,  or  benzine.  In  all  joints  meant  to  be  air-tight, 
the  use  of  rubber  packing  is  to  be  avoided.  It  answers  well 
enough  at  the  start,  but  after  several  months  it  is  sure  to 
crack  and  leak  air. 

By  an  air-tight  joint  I  do  not  mean  a  joint  which  will  not 
leak  air  under  any  pressure  w^hich  may  be  applied.  It  is  not 
necessary  that  our  pendulum  should  vibrate  in  a  vacuum; 
all  we  want  is  that  the  pressure  inside  the  clock  case  should 
be  uniform ;  that  it  should  not  vary  with  the  barometer  out- 
side. In  actual  practice  we  find  it  best  to  iTave  the  pressure 
inside  the  case  as  nearly  as  possible  equal  to  the  average 
atmospheric  pressure  outside.  Now,  if  the  barometer  in  a 
given  locality  never  sinks  below  27.5  inches,  it  is  not  neces- 
essary  that  the  vacuum  in  the  clock  case  be  less  than  that 
represented  by  29.5  inches  of  mercur)-  pressure.  So,  too, 
if  it  were  desirable  to  have  the  pressure  inside  the  case  great- 
er than  that  outside,  owing  to  some  special  form  of  joint 
which  made  the  clock  case  less  liable  to  leak  out  than  to 
leak  in,  it  might  be  that  an  inside  pressure  would  be  effi- 
cient at  31  inches  of  mercury.  By  not  having  the  inside 
pressure  vary  but  slightly  from  the  outside,  the  actual  pres- 
sure of  air  will  not  exceed  one  inch  of  mercury,  or,  say, 
y2  pound  pressure  to  the  square  inch.  This  is  a  pressure 
which  causes  quite  an  insignificant  strain  upon  any  joint. 

There  are  objections,  however,  to  the  use  of  air  in  an  en- 
closed space  for  precision  clocks  and  so  the  attempt  has  been 
made  to  tise  hydrogen.  Air  is,  comparatively  speaking, 
heavy.  It  is  14 J/2  times  as  heavy  as  hydrogen  gas,  for  in- 
stance. The  pendulum,  therefore,  in  moving  through  its 
arc  has  to  push  aside  14  times  as  much  weight  as  it  would 
have  to  in  case  it  were  surrounded  by  hydrogen.  Then 
what  might  be  called  the  ''case  friction"  is  greater  than  if 
we  used  hydrogen.  By  "case  friction"  I  mean  resistance 
and  a  disturbance  to  the  pendulum  depending  on  the  effect 
of  the  currents  of  air  produced  by  driving  the  air  before  the 


THE    MODERN    CLOCK.  ^/^g 

pendulum  against  the  sides  and  front  of  the  case.  It  is 
a  well-established  observation  that  small,  cramped  cases  dis- 
turb the  clock's  rate  more  than  large,  roomy  ones.  This  is 
because  the  air,  having  no  room  to  go  before  the  pendulum, 
is  cushioned  up  against  the  side  of  the  case  at  each  pendu- 
lum swing,  and  acts  as  a  resisting  spring  against  the  swing 
of  the  pendulum.  By  the  time  the  pendulum  has  reached 
the  end  of  its  vibration  the  air  has  escaped  upwards  and 
downwards  perhaps  so  that  it  no  longer  has  its  spring  power 
to  restore  the  loss  of  energy  to  the  pendulum.  This  "case 
friction"  is  most  pernicious  in  its  action  when  associated 
with  free  falling  weights  in  the  clock  case.  Clock  weights 
should  always  fall  in  separate  compartments,  and  never  in 
such  a  manner  that  they  can  affect  the  space  in  which  the 
pendulum  swings. 

But  this  is  a  digression  to  explain  the  term  "case  friction" 
in  its  use  in  horology. 

Precision  clocks,  almost  without  exception,  have  electric 
break-circuit  attachments  within  -the  case.  Most  of  these 
break-circuits  are  constructed  so  that  there  is  a  small  spark 
every  time  the  circuit  is  broken.  The  effect  of  such  a  spark 
in  air  is  to  convert  a  small  portion  of  the  air  in  the  imme- 
diate neighborhood  of  the  spark  into  nitrous  acid  gas. 
After  several  months  there  might  be  a  considerable  quantity 
of  this  gas  in  the  case,  with  the  certain  result  of  rusting  the 
nicer  parts  of  the  escapement. 

Many  attempts  have  been  made  to  run  a  clock  in  an 
almost  complete  vacuum  of  air;  but  the  volume  to  be  ex- 
hausted is  so  large,  and  the  leakage  is  so  sure  to  occur  after 
a  time,  that  the  attempt  is  now  pretty  generally  abandoned. 
It  will  be  inferred  from  what  has  preceded  that  a  full  atmos- 
phere of  hydrogen  would  only  offer  one-fourteenth  the  re- 
sistance to  the  pendulum  that  air  would,  and  all  the  disturb- 
ances arising  from  the  surrounding  mediums  would  be  only 
one-fourteenth  for  hydrogen  of  that  which  we  would  ex- 
pect for  air.     Every  consideration,  therefore  points  to  the 


45©  THE    MODERN    CLOCK. 

use  of  hydrogen  as  the  medium  with  which  to  fill  our  clock 
cases.  It  is  inert,  it  forms  no  compounds  under  the  influ- 
ence of  the  electric  spark,  the  case  friction  is  no  greater 
than  would  exist  if  we  made  an  air  vacuum  of  only  about  i 
inch  of  mercury,  and  hydrogen  gas  may  be  readily  prepared. 
The  method  from  dilute  sulphuric  acid  and  scrap  zinc  is  the 
handiest,  and  it  will  be  found  described  in  almost  any  chem- 
istry textbook  or  encyclopedia.  Should  the  horolo- 
gist  wish  to  know  something  of  the  chemistry  of 
the  process,  without  pervious  study,  he  will  find 
it  described  in  very  simple  language  in  any  pri- 
mary chemistry.  The  practical  details  of  filling  a  clock 
case  with  hydrogen  gas  I  have  not  yet  worked  out.  It  is 
evident  that  since  hydrogen  is  143^  times  lighter  than 
air,  that  by  attaching  a  small  tube  to  the  source  of  hydrogen 
and  to  the  top  of  the  clock  case,  and  another  small  outlet 
tube  at  the  bottom  of  the  clock  case,  that  by  gravity  alone 
the  hydrogen  would  fill  the  upper  part  of  the  case  and  drive 
the  air  before  it  out  at  the  bottom.  The  hydrogen  should 
be  dry.  To  insure  this  it  should  pass  through  a  tube  con- 
taining quicklime,  which,  if  it  is  a  foot  long  and  two  inches 
in  diameter,  will  be  sufficient.  No  burning  light  or  electric 
spark  must  be  put  into  the  case  while  filling,  because  the 
mixture  of  hydrogen  with  the  air  is  very  explosive  when 
ignited.  Great  care  must  be  used  in  making  all  joints 
when  attempting  to  maintain  an  atmosphere  of  hydrogen 
as  it  leaks  readily  through  the  pores  of  wood  iron  and  all 
joints.  It  is,  therefore,  better  to  treat  the  case  friction  as 
a  constant  element  and  simply  keep  it  constant. 
.  The  above  discussion  has  not  considered  the  temperature 
question.  It  is  important  that  the  changes  of  temperature 
in  a  clock  case  should  be  as  slow  as  possible  and  as  small  as 
possible.  Professor  Rogers,  of  the  Harvard  College  Ob- 
servatory, has  shown  that  such  bars  as  are  used  in  pendu- 
lum rods  of  clocks  are  often  several  hours  in  taking  up 
air  temperatures  m.any  degrees  different  from  that  in  which 


THE    MODERN    CLOCK.  45I 

they  were  swinging.  We  have  at  the  top  of  the  pendulum 
a  thin  spring  for  suspension  whose  temperature  decides 
its  molecular  friction ;  then  we  have  the  pendulum  rod,  and 
lastly  the  large  bob,  all  of  which  take  up  any  new  tempera- 
ture with  different  degrees  of  slowness.  Now  obviously  no 
compensation  can  be  made  to  act  unless  the  temperatures  are 
the  same  for  all  parts  of  the  pendulum,  and  vary  at  the 
same  rate.  A  number  of  years  ago,  there  was  a  long  discus- 
sion as  to  the  temperature  at  the  top  and  bottom  of  clock 
cases.  It  was  shown  that  this  regularly  amounted  to  several 
deofrees  in  the  best  clocks.  It  was  to  lessen  this  difference 
that  at  the  Harvard  College  Observatory  the  Bonds  built  a 
deep  well  in  the  cellar,  purposing  to  put  the  clock  at  its 
bottom.  The  idea  was  a  good  one,  and  were  it  not  for  the 
difficulty  in  getting  at  clocks  in  wells,  and  keeping  water 
out,  it  would  doubtless  find  favor  where  the*utm.ost  accu- 
racy is  desired. 

A  better  plan  is  to  run  the  clock  at  a  high  temperature, 
say  95°  to  100°  F.  The  oil  is  more  liquid,  the  temperature 
can  be  more  easily  maintained,  it  can  all  take  place  in  light- 
ed, dry  rooms,  and  the  means  for  doing  this  we  shall  now 
consider. 

Our  iron  case  must  now  be  housed  in  another  outside 
case,  which  had  better  be  of  wood,  with  glass  windows  for 
seeing  the  clock  face.  A  single  thickness  of  wood  would 
conduct  heat  too  rapidly.  It  must  therefore  be  made  of 
two  thicknesses,  with  an  air  space  between.  If  the  air 
space  is  left  unfilled,  the  circulation  of  the  air  soon  causes 
the  inner  wooden  layer  to  be  of  the  same  temperature  as  the 
outer.  It  is  necessary  to  prevent  this  circulation  of  air 
therefore  by  means  of  some  substance  which  is  a  non-con- 
ductor of  heat  and  which  will  prevent  the  air  from  circu- 
lating. The  very  best  thing  to  be  used  in  this  connection  is 
cotton  batting,  which  has  been  picked  out  until  it  is  as  light 
and  fibrous  as  possible.  Then  if  the  doors  and  windows 
of  the  Vv'ooden  case  are  made  of  two  thicknesses  of  extra 


452 


THE    MODERN    CLOCK. 


thick  glass,  and  are  firmly  clamped,  by  screws  through  their 
sashes  or  some  other  means,  to  the  frame  of  the  case,  we 
have  the  best  form  possible  for  our  completed  case  of  the 
type  I  have  described.  It  now  remains  to  provide  a  layer 
of  hot  water  pipes  inside  the  clock  room,  heated  by  circula- 
ting hot   water   from  the   outside.     The   flame   under  the 


DDDiDDnlDDDlDDDlnDnlDDDlODDlDDdDDDlDgDlDDD 


I  .  I    I .  I  ."m 


1     r 


HESSiigaaSiSBigiBBlESslB) 


Fig.  151.    Section  tlirough  dock  room  of  the  Waltliam  Watcli  Company 


water  tank  outside,  whether  of  gas  or  kerosine,  to  be  auto- 
matically raised  or  lowered  by  any  such  thermostat  arrange- 
ments as  are  in  common  use  with  chicken  incubators,  when 
the  temperature  varies  from  the  point  desired.  Experience 
teaches  that  the  volume  of  water  had  better  be  considerable, 
if  there  is  considerable  difference  in  the  annual  variations  of 
temperature  according  to  the  seasons.      Thus    in    Massa- 


THE    MODERN'    CLOCK.  453 

chnsetts  or  Illinois  the  temperature  is  likely  to  vary  irom 
—  30°  F.  to  +  110°  F.,  and  the  heating  arrangements  must 
be  suitable  to  take  care  of  this  variation. 

The  Waltham  Watch  Company's  clock  room  is  an  excel- 
lent example  of  the  means  taken  to  secure  uniformity  of 
temperature  and  absence  of  vibration. 

The  clock  room,  which  is  located  in  the  basement  of  one 
of  the  buildings,  is  built  with  a  double  shell  of  hollow  tile 
brick.  The  outer  shell  rests  upon  the  floor  of  the  basement, 
and  its  ceiling  is  within  two  or  three  inches  of  the  base- 
ment ceiling.  The  inner  shell  is  lo  feet  square  and  8  feet 
in  height,  measured  from  the  level  of  the  cellar  floor.  There 
is  an  i8-inch  space  between  the  walls  of  the  inner  and  outer 
shell  and  a  9-inch  space  between  the  two  ceilings.  On  the 
front  of  the  building  the  walls  are  three  feet  apart  to  ac- 
commodate the  various  scientific  instruments,  such  as  the 
chronograph,  barometer,  thermostat,  level-tester,  etc.  The 
inner  house  is  carried  down  four  feet  below  the  floor  of  the 
basement,  and  rests  upon  a  foundation  of  gravel.  The  walls 
of  the  inner  house  below  the  floor  level  consist  of  two  thick- 
nesses of  brick  with  an  air  space  between,  and  the  whole 
of  the  excavated  portion  is  lined,  sides  and  bottom,  with 
sheet  lead,  carefully  soldered  to  render  it  watertight.  At 
the  bottom  of  the  excavation  is  a  layer  of  12  inches  of  sand, 
and  upon  this  are  built  up  three  solid  brick  piers,  meas- 
uring 3  feet  6  inches  square  in  plan  by  3  feet  in  height, 
which  form  the  foundation  for  the  three  pyramidal  piers 
that  carry  the  three  clocks.  The  interior  walls  and  ceilings 
and  the  piers  for  the  clocks  are  finished  in  white  glazed 
tiling.  The  object  of  the  lead  lining,  of  course,  is  to  thor- 
oughly exclude  moisture,  while  the  bed  of  sand  serves  to 
absorb  all  waves  of  vibration  that  are  communicated 
through  the  ground  from  the  various  moving  machinery 
throughout  the  works.  At  the  level  of  the  basement  floor  a 
light  grating  provides  a  platform  for  the  use  of  the  clock 
attendants. 


454  THE    MODERN    CLOCK. 

Although  the  placing  of  the  clock  room  in  the  cellar  and 
the  provision  of  a  complete  air  space  around  the  inner  room 
would,  in  itself,  afford  excellent  insulation  against  external 
changes  of  temperature,  the  inner  room  is  further  safe- 
guarded by  placing  in  the  outer  1 8-inch  space  between  the 
two  walls  a  lamp  which  is  electrically  connected  to,  and 
controlled  by,  a  thermostat.  The  thermostat  consists  of  a 
composite  strip  of  rubber  and  metal,  which  is  held  by  a 
clamp  at  its  upper  end  and  curves  to  right  or  left  under 
temperature  changes,  opening  or  closing,  by  contact  points 
at  the  lower  end  of  the  thermostat,  the  electrical  circuit 
which  regulates  the  flame  of  the  lamp.  The  thermostat  is 
set  so  as  to  maintain  the  space  between  the  two  shells  at  a 
temperature  which  shall  insure  a  constant  temperature  of 
71  degrees  in  the  inner  clock  house.  This  it  does  with  such 
success  that  there  is  less  than  half  a  degree  of  daily 
variation. 

The  two  clocks  that  stand  side  by  side  in  the  clock  room 
serve  to  keep  civil  time,  that  is  to  say,  the  local  time  at  the 
works.  The  clock  to  the  right  carries  a  twelve-hour  dial 
and  is  known  as  the  mean-time  clock.  By  means  of  elec- 
trical connections  it  sends  time  signals  throughout  the  whole 
works,  so  that  each  ■  operative  at  his  bench  may  time  his 
watch  to  seconds.  The  other  clock,  known  as  the  astronom- 
ical clock,  carries  a  twenty-four-hour  dial,  and  may  be  con- 
nected to  the  works,  if  desired.  These  two  clocks  serve  as  a 
check  one  upon  the  other.  They  were  made  at  the  works 
and  they  have  run  in  periods  of  over  two  months  with  a 
variation  of  less  than  0.3  of  a  second,  or  1-259,000  part  of  a 
day.  The  third  clock,  which  stands  to  the  rear  of  the  other 
two,  is  the  sidereal  clock.  It  is  used  in  connection  with  the 
observatory  work,  and  serves  to  keep  sidereal  or  star  time. 

The  rate,  as  observed  at  the  Waltham  works,  rarely  ex- 
ceeds one-tenth  of  a  second  per  day.  That  is  to  say,  the 
sidereal  clock  will  vary  only  one  second  in  ten  days,  or 
three  seconds  in  a  month.    The  variation,  as  found,  is  cor- 


THE    MODERN    CLOCK.  455 

rected  by  adding  or  subtracting  weights  to  or  from  the 
penduhim,  the  weights  used  being  small  disks,  generally  of 
aluminum. 

Summing  up,  then,  we  find  that  the  great  accuracy  ob- 
tained in  this  clock  room  is  due  to  the  careful  elimination 
of  the  various  elements  that  would  exercise  a  disturbing  in- 
fluence. Changes  of  temperature  are  reduced  to  a  minimum 
by  insulation  of  the  clock  house  within  an  air  space,  in 
which  the  temperature  is  automatically  maintained  at  an 
even  rate.  Changes  of  humidity  are  controlled  by  the  spe- 
cially designed  walls,  by  the  lead  sheathing  of  the  founda- 
tion pit,  by  the  preservation  of  an  even  temperature,  and 
by  placing  boxes  of  hygroscopic  material  within  the  inner 
chamber.  Errors  due  to  vibration  are  eliminated  by  plac- 
ing the  clocks  on  massive  masonry  piers  which  stand  upon 
a  bed  of  sand  as  a  shock-absorbing  medium. 

The  astronomical  clock  is  inclosed  in  a  barometric  case, 
fitted  with  an  air  pump,  by  which-  the  air  may  be  exhausted 
and  the  pendulum  and  other  moving  parts  relieved  from 
barometric  disturbances.  For  it  must  be  understood  that 
variation  in  barometric  pressure  means  a  variation  in  the 
density  of  the  air,  and  that  the  speed  of  the  pendulum  must 
necessarily  be  affected  by  such  changes  of  density. 

Restoring  Old  Cases. — Very  often  the  watchmaker  gets 
a  clock  which  he  knows  will  be  vastly  improved  by  varnish, 
but  not  knowing  how  to  take  off  the  old  varnish  he  simply 
gives  it  a  little  sand  paper  or  rubs  it  oft  with  oil  and  lets  it 
go  at  that.  Varnishing  such  a  clock  thinly  with  equal  parts 
of  boiled  oil  and  turpentine  and  allowing  it  to  dry  will  often 
restore  the  transparency  of  the  varnish ;  if  uneven  results 
are  obtained  a  second  coat  may  be  necessary.  Many  of 
these  old  clocks  have  not  been  varnished  for  so  many  years 
that  the  covering  of  the  wood  looks  like  a  cheap  brown 
paint.  To  remove  this  in  the  ordinary  way  means  endless 
labor,  and   if  the  case  is  inlaid  with  colored  patterns  of 


456  THE    MODERN    CLOCK. 

veneers,  which  are  partly  loosened  by  the  glue  drying  out, 
the  repairer  is  afraid  to  touch  it  for  fear  he  will  only  make 
matters  worse  in  the  attempt  to  better  them. 

In  the  case  of  an  old  clock  of  inlaid  marquetry,  if  the 
pieces  of  veneer  have  become  partly  loosened,  the  first  thing 
to  do  is  to  make  a  thin,  fresh  glue.  Work  the  glue  under 
the  veneer  and  then  clamp  it  down  tightly  with  a  piece  of 
oiled  paper,  or  waxed  paper,  laid  between  the  glue  and  the 
board  used  to  clamp  with  and  the  whole  firmly  set  down 
tight  with  screws  or  screw  clamps.  To  make  waxed  paper 
dissolve  paranne  wax  in  benzine  and  flow  or  brush  on  the 
paper  and  let  dry.  After  the  glue  has  hardened  comes  the 
work  of  removing  the  varnish.  To  do  this  you  will  need 
some  varnish  remover,  which  can  either  be  bought  at  the 
paint  store,  or  made  as  follows : 

Varnish  Remover. — In  doing  such  work  the  trick  is  to 
make  sure  that  nothing  put  on  the  case  will  injure  it,  as  a 
clock  one  hundred  years  old  cannot  be  replaced.  Therefore, 
if  you  are  suspicious  as  to  the  varnish  removers  you  can 
purchase,  and  do  not  want  to  take  chances,  you  may  make 
one  of  wood  alcohol  and  benzole,  or  coal  tar  naphtha.  Be 
sure  you  do  not  get  petroleum  naphtha,  which  is  common 
gasoline.  The  coal  tar  naphtha  is  a  wood  product.  The 
wood  alcohol  is  also  a  wood  product  and  the  varnishes  used 
upon  furniture  are  vegetable  gums,  so  that  it  will  readily 
be  seen  that  you  are  putting  nothing  on  the  antique  with 
which  it  was  not  associated  in  its  natural  state.  Equal  parts 
of  benzole  and  wood  alcohol  will  dissolve  gums  instantane- 
ously, so  that  if  the  oil  has  dried  out  of  the  varnish  so  much 
that  the  varnish  has  become  opaque  and  only  the  rosins  are 
left,  the  application  of  this  fluid  with  a  brush  will  cause  in- 
stant solution,  making  the  gums  boil  up  and  form  a  loose 
crust  upon  the  surface  of  the  wood,  as  the  liquid  evaporates, 
which  it  does  very  rapidly. 


THE    MODERN    CLOCK.  457 

Varnishes  containing  shellac  and  some  other  gums  are 
rather  hard  to  dissolve  and  where  an  obstinate  varnish  is  en- 
countered it  may  be  well  to  use  wax  in  the  varnish  remover. 
This  is  done  by  shaving  or  chopping  some  parafine  wax, 
dissolving  it  in  the  benzole,  and  when  it  is  clear  and  trans- 
parent, add  the  wood  alcohol.  Upon  the  addition  of  the 
alcohol  the  wax  immediately  curdles  so  that  the  fluid  be- 
comes milky.  In  this  condition  it  is  readily  brushed  upon 
any  surface  and  when  the  wax  strikes  the  air  it  congeals  and 
forms  a  crust  which  holds  the  liquid  underneath  and  enables 
it  to  do  its  work  instead  of  evaporating. 

The  wax  also  serves  the  purpose  of  allowing  the  workman 
to  see  just  where  he  Is  putting  his  fluid  and  of  holding  it  in 
position  upon  vertical  surfaces  or  ceilings,  round  moldings, 
carved  work  and  other  places  from  which  it  will  quickly 
run  off.  Only  enough  wax  should  be  added  to  make  it 
spread  readily  with  the  brush  and  after  soaking  it  will  be  an 
easy  matter  to  take  a  painter's  putty  knife,  a  case  knife,  or  a 
scraper  and  laying  it  nearly  flat  on  the  wood  remove  all  the 
varnish  at  one  operation,  wiping  off  the  knife  as  fast  as  it 
becomes  too  full.  After  the  bulk  of  the  varnish  Is  off  some 
of  the  fluid,  without  the  wax,  may  be  used  upon  a  cloth  to 
go  over  and  smooth  up  by  removing  the  spots  and  stripes  of 
varnish  left  by  the  knife,  or  in  moldings,  etc.,  where  the 
knife  cannot  be  applied,  and  we  have  our  bare  wood,  which, 
after  drying  and  sand  papering,  is  ready  for  a  fresh  coat  of 
XXX  coach  varnish,  which  should  dry  in  24  hours  and 
harden  in  a  week. 

A  very  little  work  and  practice  in  this  will  enable  the 
workman  to  rapidly  and  cheaply  clean  up  and  repair  an- 
tiques in  such  a  way  that  it  will  add  greatly  to  his  repu- 
tation. 

To  restore  the  gloss  of  polished  wood  it  Is  not  always  the 
best  plan  to  employ  true  furniture  polish.  The  majority  of 
the  so-called  polishes  for  wood  are  based  on  a  mixture  of 
boiled  linseed  oil  and  shellac  varnish,  made  by  dissolving 


45^  THE    MODERN    CLOCK. 

shellac  in  alcohol  in  the  proportion  of  four  ounces  of  shellac 
to  a  pint  of  alcohol.  A  little  of  the  dissolved  shellac  is 
poured  on  to  a  canton-flannel  rag,  a  few  drops  of  the  boiled 
linseed  oil  are  placed  on  the  cloth,  and  the  wood  to  be  pol- 
ished is  rubbed  vigorously.  About  half  an  ounce  of  cam- 
phor gum  dissolved  with  the  shellac  in  the  alcohol  will 
greatly  facilitate  the  operation  of  polishing. 

A  soft  woolen  rag,  moistened  with  olive  oil  and  vigorously 
rubbed  on  dull  varnished  surfaces,  like  old  clock  cases,  will 
brighten  the  surface  wonderfully.  Some  workmen  add  a 
few  drops  of  a  strong  solution  of  camphor  gum  in  alcohol 
to  the  olive  oil. 

The  polishing  of  cases  is  accompHshed  by  applying  sev- 
eral coats  of  the  best  coach  painters'  rubbing  varnish,  when, 
after  perfect  drying,  the  surface  is  rubbed  with  a  felt  or  a 
canton-flannel  rag,  folded  flat,  using  water  and  the  finest 
pulverized  pumic  stone.  This  operation  smooths  the  sur- 
faces. The  final  polishing  of  such  work  is  done  by  rubbing 
with  rotten  stone  and  olive  oil  with  the  smooth  side  of 
canton  flannel.  To  remove  the  last  traces  of  smear  caused 
by  the  oil,  an  old,  soft  linen  cloth  and  rye  flour  is  used.  Of 
course,  fine  work  like  we  see  on  new  cases  of  fine  quality  is 
not  likely  to  be  produced  by  one  who  is  unaccustomed  to  it; 
a  man  must  serve  a  good,  long  apprenticeship  in  the  varnish 
finishing  business  before  he  is  competent  for  it;  and  even 
then  some  polishers  fail  to  obtain  the  fine  results  achieved  by 
others.  The  great  danger  is  that  the  rubber  will  cut 
through  the  varnish  and  expose  the  bare  wood  on  edges,  cor- 
ners and  even  in  spots  on  plane  surfaces,  before  he  has  re- 
moved the  lumps  and  streaks  of  varnish  on  adjacent  portions 
of  the  work.  Whenever  the  varnish  is  flat  and  smooth  in 
any  spot,  you  must  stop  rubbing  there. 

Black  wood  clocks  which  have  become  smoked  and  dull 
should  have  the  cases  rubbed  with  boiled  oil  and  turpentine 
on  a  piece  of  soft  woolen  rag ;  afterwards  polish  off  with 
a  dry  rag.    If  the  gloss  has  been  destroyed  it  will  have  to  be 


THE    MODERN    CLOCK.  459 

varnished.  Flow  the  varnish  well  on  and  use  i^-inch 
brush  and  be  careful  to  get  the  varnish  on  even  and  so  as  not 
to  trickle.  This  is  easy  if  you  are  careful  to  keep  the  var- 
nish thin  and  do  not  go  over  the  varnish  a  second  time 
after  spreading  it  on.  Thin  with  turpentine  and  put  very 
little  on  the  case ;  it  is  already  smooth  and  a  mere  film  will 
give  the  gloss.  For  white  filling  on  the  engraving  on  black 
cases  use  Chinese  white  or  get  a  good  white  enamel  at  a 
paint  store. 

Gilding  on  wood  cases  is  done  by  mixing  a  little  yellow 
dry  color  with  thin  glue  and  painting  the  cases  with  the 
mixture ;  the  color  lets  you  see  what  you  are  doing.  When 
the  glue  has  dried  until  it  is  "tacky,"  lay  gold  leaf  on  the 
painted  portions  and  smooth  down  with  cotton.  If  you  have 
any  holes  do  not  attempt  to  patch  them.  It  is  easier  and 
quicker  to  put  on  another  sheet  of  gold  leaf  over  the  first 
one.  After  the  gold  is  dry,  it  may  be  burnished  with  a 
bloodstone  or  smooth  steel  burnisher,  or  it  may  be  left  dead. 
Finish  with  colorless  lacquer,  very  thin  and  smooth. 

Imitation  gold  leaf,  known  to  the  trade  as  Dutch  Mietal, 
may  be  substituted  for  the  gold  leaf,  if  the  latter  is  thought 
to  be  too  expensive,  but  in  such  cases  be  sure  to  have  the 
metal  well  covered  with  the  lacquer,  as  unless  this  is  done 
it  will  blacken  in  two  or  three  years — sometimes  in  two  or 
three  months. 

Bronze  powder  may  be  applied  to  the  glue  size  with  a  tuft 
of  cotton  and  well  rubbed  in  until  flat  and  smooth ;  then 
lacquer  and  dry.  Never  put  on  bronze  paint,  for  the  follow- 
ing reason :  If  we  examine  the  bronze  under  a  microscope 
we  shall  find  that  it  is  composed  of  flat  scales  like  fish  scales; 
if  mixed  as  a  paint  they  will  be  found  lying  at  all  angles  in 
the  painted  work — many  standing  on  edge.  Such  scales 
reflect  the  light  away  from  the  eye  and  make  the  work  look 
dull  and  rough.  If  we  rub  these  dry  scales  in  gently  on  the 
sticky  size,  we  will  lay  them  all  down  flat  and  smooth,-  so 
that  the  work  will  glisten  all  over  with  an  even  color.     Al- 


460  THE    MODERN    CLOCK. 

ways  lacquer  bronzed  work — yellow  lacquer  being  the  best 
— and  put  on  plenty  of  lacquer. 

Metal  ornaments,  when  discolored,  should  be  removed 
from  the  case,  dipped  in  boiling  lye  to  remove  the  lacquer, 
scratch  brushed,  dipped  in  ammonia  to  brighten,  rinsed  in 
hot  water  and  dried  in  sawdust.  They  may  then  be  lac- 
quered with  a  gold  lacquer,  or  plated  in  one  of  the  gold 
plating  solutions  sold  by  dealers  for  plating  without  a  bat- 
tery and  then  lacquered,  if  bright.  If  they  are  of  oxidized 
finish  cleaning  and  lacquering  is  generally  all  that  is  neces- 
sary. 

Oxidized  metal  cases,  if  badly  discolored,  should  be  sent 
to  an  electroplater  to  be  refinished,  as  the  production  of 
smooth  and  even  finishes  on  such  cases,  requires  more  skill 
than  the  clock  repairer  possesses,  and  he  therefore  could 
not  do  a  good  job,  even  if  he  had  the  necessary  materials 
and  formulae. 

Marble  cases  are  made  of  slabs,  cemented  together. 
Many  workmen  use  plaster  of  paris  by  merely  mixing  it 
with  water,  though  we  rather  think  it  better  to  use  glue  in 
the  mixing,  as  plaster  so  mixed  will  not  set  as  quickly  as 
that  mixed  with  water.  After  the  case  is  cemented  with  the 
plaster,  the  workman  can  go  over  the  joint  with  a  brush  and 
water  colors,  and  with  a  little  care  should  be  able  to  turn 
out  a  job  in  which  the  joint  will  not  be  noticeable.  Another 
cement  much  used  for  marble  is  composed  of  the  white  of 
an  egg  mixed  with  freshly  slaked  lime,  but  it  has  the  dis- 
advantage of  setting  very  quickly. 

Marble  case  makers  use  a  cement  composed  of  tallow, 
brick  dust,  and  resin  melted  together,  and  it  sets  as  hard 
as  stone  at  ordinary  temperatures. 

It  often  happens  that  the  marble  case  of  a  mantel  clock 
is  injured  by  some  accident  and  its  corners  are  generally 
the  first  to  suffer.  If  the  break  is  not  so  great  as  to  war- 
rant a  new  case  or  a  new  part  the  repairer  may  make  the 


THE    MODERN    CLOCK.  461 

case  a  little  smaller  or  file  until  the  edges  are  reproduced, 
after  which  the  polish  is  restored.     Proceed  as  follows : 

Take  off  from  the  damaged  part  as  much  as  is  necessary 
by  means  of  a  file,  taking  care  however,  not  to  alter  the 
original  shape  of  the  case.  Now  grind  off  the  piece  worked 
with  the  file  with  a  suitable  piece  of  pumice  stone  and 
water  and  continue  the  grinding  next  with  a  water  stone 
until  all  the  scratches  have  disappeared,  paying  special  at- 
tention to  the  corners  and  contours.  After  this  has  been 
done  take  a  hard  ball  of  linen,  moisten  it,  and  strew  over 
it  either  tripoli  or  fine  emery  and  proceed  to  polish  the 
case  with  this.  Finish  the  polishing  with  another  linen 
ball,  using  on  it  still  finer  emery  and  rouge.  Now  dry  the 
case  and  finish  the  polishing  with  a  mixture  of  beeswax 
and  oil  of  turpentine.  This  method  may  be  employed  for 
all  kinds  of  marble,  or  onyx  and  alabaster  cases. 

In  cases  where  the  fractures  are  very  deep,  so  that  the 
object  cannot  be  made  much  smaller  without  ruining  the 
shape,  the  damaged  parts  may  be  filled  with  a  cement,  pre- 
pared from  finely  powdered  marble  dust  and  a  little  isin- 
glass and  water,  or  fish  glue  wall  answer  very  well.  Stir 
this  into  a  thick  paste,  which  fill  into  the  deep  places  and 
permit  to  dry ;  after  drying,  correct  the  shape  and  polish 
as  described. 

If  the  pieces  which  have  been  broken  off  are  at  hand 
they  may  be  cemented  in  place  again.  Wet  the  pieces  with 
a  solution  of  water  and  silicate  of  potash,  insert  them  in 
place  and  let  them  dry  for  forty-eight  hours.  If  the  case 
is  made  of  white  marble  use  the  white  of  an  egg  and  a 
little  Vienna  lime,  or  common  lime  will  answer. 

To  Polish  Marble  Clock  Cases. — It  frequently  be- 
comes the  duty  of  the  repairer  to  restore  and  polish  marble 
clock  cases,  and  we  would  recommend  him  to  make  a  thin 
paste  of  the  best  beeswax  and  spirits  of  turpentine,  clean 
the  case  well  from  dust,  etc.,  then  slightly  cover  it  with 


462  THE    MODERN    CLOCK. 

the  paste,  and  with  a  handful  of  clean  cotton,  rub  it  well, 
using  abundant  friction,  finish  off  with  a  clean  old  linen 
rag,  which  will  produce  a  brilliant  black  polish.  For  light 
colored  marble  cases,  mix  quicklime  with  strong  soda  water, 
and  cover  the  marble  with  a  thick  coating.  Glean  off  after 
twenty-four  hours,  and  polish  well  with  fine  putty  powder. 
To  Remove  Oil  Spots  From  Marble. — Oil  spots,  if  not 
too  old,  are  easily  removed  from  marble  by  repeatedly  cov- 
ering them  with  a  paste  of  calcined  magnesia  and  benzine, 
and  brushing  off  the  magnesia  after  the  dissipation  of  the 
oil;  this  may  have  to  be  repeated  several  times.  Another 
recipe  reads  as  follows :  Slaked  lime  is  mixed  with  a  strong 
soap  solution,  to  the  consistency  of  cream;  this  is  placed 
upon  the  oil  spot,  -and  repeated  until  it  has  disappeared.  In 
place  of  this  mixture,  another  one  may  be  used,  consisting 
of  an  ox  gall,  125  grains  of  soapmaker's  waste  lye  and  62^ 
grams  of  turpentine,  with  pipe  clay,  to  the  consistency  of 
dough. 

Cutting  Clock  Glasses. — You  will  sometimes  want  a 
new  glass  for  a  clock.  I  get  a  lot  of  old  5x7  negatives  and 
scald  the  film  off  in  plain  hot  water,  rinse  well  and  dry. 
Now  I  lay  my  clock  bezel  on  a  piece  of  paper  and  trace 
around  with  a  pencil,  inside  measure.  Now  remove  the 
bezel  and  trace  another  circle  around  the  outside  of  this 
circle  about  one-eighth  inch.  Now,  lay  the  paper  on  a 
good,  solid,  smooth  surface,  glass  on  top,  and  with  a  com- 
mon wheel  glass-cutter  follow  around  the  outside  line,  free 
handed,  understand.  The  paper  with  marked  circle  on  is 
under  the  glass,  and  you  can  see  right  through  the  glass 
where  to  follow  with  the  cutter.  Now  cut  the  margins  of 
glass  so  as  to  roughly  break  out  to  one-half  inch  of  your 
circle  cut,  running  the  cuts  out  on  the  side,  then  carefully 
break  out. 


CHAPTER  XXIV. 

SOME  HINTS  ON  MAKING  A  REGULATOR. 

Of  all  the  instruments  used  by  a  watchmaker  in  the 
prosecution  of  his  business,  there  is  probably  none  more 
iniportant  than  his  regulator.  Its  purpose  is  to  divide  time 
into  seconds,  and  it  is  the  standard  by  which  the  practical 
results  of  his  labors  are  tested ;  the  guide  which  all  the 
other  time-keepers  in  his  possession  are  made  to  follow  and 
the  arbitrator  which  settles  all  disputes  regarding  the  per- 
formance of  his  watches. 

No  regulator  has  yet  been  constructed  that  contains  with- 
in itself  every  element  for  producing  absolutely  accurate 
time-keeping.  At  intervals  they  must  all  be  corrected  from 
some  external  source,  such  as  comparison  with  another 
time-keeper,  the  error  of  which  is  known,  or  by  the  motion 
of  the  heavenly  bodies,  when  instruments  for  that  purpose 
are  available.  Before  beginning  to  make  a  regulator,  the 
prudent  watchmaker  will  first  reflect  on  the  various  plans  of 
constructing  all  the  various  details  of  an  accurate  time- 
keeper, and  select  the  plan  which,  in  his  opinion,  or  in  the 
opinion  of  those  whom  he  may  consult  on  the  subject,  will 
best  accomplish  the  object  he  has  in  view. 

In  former  3-ears  a  regulator  case  was  made  with  the  sole 
object  of  accommodating  the  requirements  of  the  regulator, 
and  every  detail  in  the  construction  of  the  case  was  made 
subservient  to  the  necessities  of  the  clock.  The  plain,  well- 
made  cases  of  former  years  are  now  almost  discarded  for 
those  of  more  pretentious  design.  If  the  general  change  in 
the  public  taste  demands  so  much  display,  there  can  be  no 
objection.     It  is  perfectly  harmless  to  the  clock,  if  the  de- 

463 


464  THE    MODERN    CLOCK. 

signers  and  makers  of  the  cases  would  only  remember  that 
narrow  waists  or  narrow  necks  on  a  case,  although  part  of 
an  elegant  design,  do  not  afford  the  necessary  room  for  the 
weight  and  freedom  of  the  pendulum;  that  the  doors  and 
other  openings  in  the  case  must  be  constructed  with  a  view 
to  exclude  dust ;  and  that  the  back  should  be  made  of  thick, 
well-seasoned  hardwood,  such  as  oak  or  maple,  so  as  to 
afford  the  means  of  obtaining  as  firm  a  support  for  the  pen- 
dulum as  possible. 

When  a  regulator  case  is  known  to  have  been  made  by  an 
inexperienced  person,  which  sometimes  happens,  or  when 
we  already  have  a  case,  it  is  always  the  safest  course  for 
those  who  make  the  clock  to  examine  the  case  personally 
and  see  the  exact  accommodation  there  is  for  the  clock. 
Sometimes,  when  we  know  beforehand,  we  can,  without 
violating  any  principle,  vary  the  construction  a  little,  so  as 
to  make  the  weight  clear  the  woodwork  of  the  inside  of  the 
case,  and  in  other  respects  complete  the  regulator  in  a  more 
workmanlike  manner  by  making  the  necessary  alterations 
in  the  clock  at  the  beginning  of  its  construction,  instead  of 
after  it  has  been  once  finished  agreeably  to  some  stereotyped 
arrangement. 

The  arrangement  of  the  mechanism  of  an  ordinary  regu- 
lator is  a  simple  operation  compared  with  some  other 
horological  instruments  of  a  more  complex  character.  We 
are  not  limited  in  room  to  the  same  extent  as  in  a  watch, 
and  the  parts  being  few  in  number  a  regulator  is  m.ore 
easily  planned  than  timekeepers  having  striking  or  auto- 
matic mechanism  for  other  purposes  combined  with  them; 
yet  it  often  happens  that  the  inexperienced  make  serious 
blunders  in  planning  a  regulator,  and,  as  the  clock  ap- 
proaches completion,  many  errors  make  themselves  visible, 
which  might  have  been  avoided  by  the  exercise  of  a  little 
more  forethought.  It  may  be  that,  when  the  dial  is  being 
engraved,  the  circles  do  not  come  in  the  right  position,  or 
the  weight  comes  too  close  to  the  pendulum,  or  the  case. 


THE    MODERN    CLOCK.  46s 

or  the  cord  comes  against  a  pillar,  or  other  faults  of  greater 
or  less  importance  appear,  all  of  which  might  have  been  ob- 
viated by  taking  a  more  comprehensive  view  of  the  subject 
before  beginning  to  make  the  clock.  The  best  way  to  do 
this  is  to  draw  a  plan  and  side  and  front  elevations  to  a 
scale. 


Fig.  152 

The  position  which  the  barrel  and  great  wheel  should 
occupy  is  worthy  of  serious  consideration.  In  most  of  the 
cheap  regulators,  as  well  as  in  a  few  of  a  more  expensive 
order,  the  barrel  is  placed  in  a  direct  line  below  the  center 
wheel,  as  is  shown  in  Fig.  152.  This  arrangement  admits 
of  a  very  compact  movement,  and  it  also  allows  the  weight 
to  hang  exactly  in  the  center  of  the  case,  which  some  think 


466  THE    MODERN    CLOCK. 

looks  better  than  when  it  hangs  at  the  side,  especially  when 
there  is  a  glass  door  in  the  body  of  the  case.  But  while  a 
weight  hanging  in  the  center  of  a  case  may  be  more  pleas- 
ing to  the  eye  than  when  it  hangs  at  the  side,  this  is  an  in- 
stance where  looks  can,  with  great  propriety,  be  sacrificed 
for  utility,  because  when  the  weight  hangs  in  the  center  it 
comes  too  close  to  the  pendulum,  and  is  very  liable  to  dis- 
turb its  motion.  In  proof  of  this  statement,  let  any  reader 
who  has  a  regulator  with  a  light  pendulum  and  a  com- 
paratively large  weight  hanging  in  front  of  it,  closely  watch 
the  length  of  the  arc  the  pendulum  vibrates  when  the  weight 
is  newly  wound  up  and  when  it  is  down  opposite  the  pen- 
dulum ball,  and  he  w411  observe  that  the  length  of  vibration 
of  the  pendulum  varies  from  five  to  fifteen  minutes  of  arc, 
according  to  the  position  in  which  the  weight  is  placed ; 
that  the  pendulum  will  vibrate  larger  arcs  when  the  weight 
is  above  or  below  the  ball  than  when  it  is  opposite  it ;  and 
if  the  clock  has  a  tendency  to  stop  from  any  cause,  that  it 
will  generally  do  so  more  readily  when  the  weight  is  op- 
posite the  pendulum  ball  than  when  it  is  in  any  other  posi- 
tion. For  this  reason  I  would  dispense  with  the  symetrical 
looks  of  the  weight  hanging  in  the  center  of  the  case,  wdiich, 
after  all,  is  only  a  matter  of  taste,  and  construct  the  move- 
ment so  that  the  weight  will  hang  at  the  side,  and  as,  far 
away  from  the  pendulum  as  possible. 

Fig.  153  is  intended  to  represent  the  effect  which  plac- 
ing the  barrel  at  either  side  has  on  throwing  the  w^eight 
away  from  the  pendulum.  A  is  the  center  wheel ;  B  and  C 
are  the  great  wheels  and  barrels  with  weights  hanging  from 
them;  D  is  the  pendulum.  It  will  be  noticed  by  the  dia- 
gram that  the  weight  at  the  left  of  the  pendulum  is  exactly 
the  diameter  of  the  barrel  farther  away  from  the  pendulum 
than  the  weight  on  the  right.  On  close  inspection  it  will 
also  be  observed  that  on  the  barrel  C  the  force  of  the  weight 
is  applied  between  the  axis  of  the  barrel  and  the  teeth  of 
the  wheel,  while  on  the  barrel  B  the  axis  of  the  barrel  lies 


THE    MODERN    CLOCK. 


467 


between  the  point  where  the  force  is  appHed  and  the  point 
where  the  teeth  act  on  the  pinion ;  consequently  a  httle  more 
of  the  effective  force  of  the  weight  is  consumed  by  the 
extra  amount  of  pressure  and  friction  on  the  pivots  of  the 
barrel  B  than  there  is  in  C. 

Notwithstanding  this  disadvantage,  I  would  for  a  regu- 
lator recommend  the  barrel  to  be  placed  at  the  left  side  of 


,.  Fig.  153 

the  center  wheel,  because  the  weight  may  thereby  be  led  a 
sufficient  distance  from  the  pendulum  in  a  simple  manner. 
If  we  place  the  barrel  at  the  right,  and  thereby  secure  the 
greatest  effective  force  of  the  weight,  and  then  lead  the 
weight  to  the  side  by  a  pulley,  we  will  lose  a  great  deal 
more  by  the  friction  of  the  pulley  than  we  gain  by  the 
proper  application  of  the  weight. 

In  a  regulator  with  a  Graham  escapement  but  little  force 
is  required  to  keep  it  going,  and  there  is  usually  accommo- 


468  THE    MODERN    CLOCK. 

dation  for  an  abundance  of  power ;  therefore  we  cannot  use 
a  little  of  this  superabundant  available  force  to  better  ad- 
vantage than  by  placing  the  barrel  at  the  left  side  of  the 
clock,  and  thereby  throw  the  weight  a  sufficient  distance 
from  the  pendulum  in  the  simplest  manner. 

The  escapement  we  assume  to  be  the  old  dead  beat,  as  for 
tim.e-keeping  it  is  equal  to  a  gravity  escapement  while  pos- 
sessing advantages  undesirable  to  sacrifice  for  a  doubtful 
improvement.  The  advantages  it  possesses  over  any  form 
of  gravity  escapement  are :  it  has  fewer  pieces  and  not  so 
many  wheels ;  it  takes  very  much  less  power  to  drive ;  is  not 
liable  to  fail  in  action  while  winding,  if  the  maintaining 
power  should  be  rather  weak;  while  for  counting,  seconds 
and  estimating  fractions,  its  clear,  definite,  and  equable  beat 
has  great  superiority  over  the  complication  of  noises  made 
by  a  gravity  escapement. 

Full  directions  for  making  this  and  other  escapements 
have  already  been  given,  but  in  a  regulator  there  are  some 
considerations  which  will  not  be  encountered  in  connection 
with  the  escapements  of  ordinary  clocks,  where  fine  time- 
keeping is  not  expected.  We  have  previously  stated  that 
the  center  of  suspension  of  the  pendulum  should  be  exactly 
in  line  with  the  axis  of  the  escapement  and  we  will  now 
endeavor  to  state  plainly  how  important  this  Is  in  a  fine 
clock  and  the  reasons  for  it.  Mr.  Charles  Frodsham,  the 
noted  English  chronomiCter  maker,  has  conducted  a  series  of 
careful  experiments  and  the  results  were  communicated  in 
a  report  to  the  British  Horological  Society,  as  follov/s : 

When  we  talk  of  detached  escapements,  or  any  escape- 
ment applied  to  a  pendulum,  it  is  necessary  to  bear  in  mind 
that  there  is  always  one-third  at  the  least  of  the  pendulum's 
vibration  during  which  the  arc  of  escapement  is  intimately 
mixed  up  with  the  vibration,  either  in  locking,  unlocking, 
or  in  giving  impulse;  therefore,  whatever  inherent  faults 
any  escapement  may  possess  are  constantly  mixed  up  in  the 
result;  the  words  ''detached  escapement"  can  hardly  be  ap- 


THE    IVODERN    CLOCK  469 

plied  when  the  entire  arc  of  vibration  is  only  two  degrees ; 
or,  in  other  words,  what  part  of  the  vibration  is  left  with- 
out the  influence  of  the  escapement? — at  most  one  degree. 
In  chronometers  the  arc  of  vibration  is  from  ten  to  fifteen 
times  greater  than  the  arc  of  escapement. 

The  dead-beat  escapement  has  been  accused  of  interfer- 
ing with  the  natural  isochronism  of  the  pendulum  by  its 
extreme  friction  on  the  circular  rests,  crutch,  and  difficulty 
of  unlocking,  etc.,  all  of  which  we  shall  show  is  only  so 
when  improperly  made. 

When  the  dead-beat  escapement  has  been  mathematically 
constructed,  and  is  strictly  correct  in  all  its  bearings,  its  vi- 
brations are  found  to  be  isochronous  for  arcs  of  different 
extent  from  0.75  of  a  degree  to  2.50  degrees ;  injurious 
friction  does  not  then  exist;  the  run  up  on  the  locking  has 
no  influence,  nor  is  there  any  friction  at  the  crutch ;  oil  is 
not  absolutely  necessary,  except  at  the  pivots;  and  there 
is  no  unlocking  resistance  nor  any  inclination  to  repel  or 
attract  the  wheel  at  its  lockings. 

The  general  mode  of  making  this  escapement  is  very  de- 
fective and  indefinite,  and  entirely  destroys  the  naturally 
isochronous  vibration  of  the  pendulum. 

The  following  is  the  usual  rate  of  the  same  pendulum's 
performance  in  the  different  arcs  of  vibration  with  an 
escapement  as  generally  constructed  after  empirical  rules : 

Arc  of  vibration  3°  rate  per  diem  9.0  seconds. 

Arc  of  vibration  2^°  rate  per  diem  6.0  seconds. 

Arc  of  vibration  2°  rate  per  diem  3.5  seconds. 

Arc  of  vibration  ij4°  rate  per  diem  1.5  seconds. 

Arc  of  vibration  1°  rate  per  diem  0.0  seconds. 

Thus  for  a  change  of  vibration  of  1°,  we  have  a  daily  er- 
ror of  3.5.  No  change  of  suspending  spring  will  alter  in- 
herent mechanical  errors  destructive  of  the  laws  of  motion. 
With  clocks  made  in  the  usual  manner,  whether  you  apply 
a  long  or  short  spring,  strong  or  weak,  broad  or  narrow, 


4.70  THE    MODERN    CLOCK. 

you  will  not  remove  one  fraction  of  the  error ;  so  the  sooner 
the  fallacy  of  relying  upon  .the  suspending  spring  to  cure 
mechanical  errors  is  exploded  the  better. 

That  the  suspending  spring  plays  a  most  important  part 
must  be  admitted,  since,  when  suspended  by  a  spring,  a 
pendulum  is  kept  in  motion  by  a  few  grains  only,  whereas, 
if  supported  on  ordinary  pivots,  200  lbs.  weight  would  not 
drive  it  2'  beyond  its  arc  of  escapement,  so  great  would  be 
the  friction  at  the  point  of  suspension. 

The  conditions  on  which  alone  the  vibrations  of  the  pen- 
dulum will  be  isochronous  are  the  following: 

1.  That  the  pendulum  be  at  time  with  and  without  the 
clock,  in  which  state  it  is  isochronous  "suspended  by  a 
spring." 

2.  That  the  crutch  and  pallets  shall  each  travel  at  the 
same  precise  angular  velocity  as  the  pendulum,  which  can 
only  happen  when  the  arc  ^ach  is  to  describe  is  in  direct 
proportion  to  its  distance  from  the  center  of  motion,  that 
is,  from  the  pallet  axis. 

3.  That  the  angular  force  communicated  by  the  crutch 
to  the  pendulum  shall  be  equal  on  both  sides  of  the  quiescent 
point;  or,  in  other. words,  that  the  lead  of  each  pallet  shall 
be  of  the  same  precise  amount. 

4.  That  any  number  of  degrees  marked  by  the  crutch  or 
pallets  shall  correspond  with  the  same  number  of  degrees 
shown  by  the  lead  of  the  pendulum,  as  marked  by  the  index 
on  the  degree  plate. 

5.  That  the  various  vibrations  of  the  pendulum  be 
driven  by  a  motive  weight  in  strict  accordance  with  the 
theoretical  law ;  that  is,  if  a  5-lb.  weight  cause  the  pendulum 
to  double  its  arc  of  escapement  of  1°,  and  consequently 
drive  it  2°,  all  the  intermediate  arcs  of  vibration  shall  in 
practice  accord  with  the  theory  of  increasing  or  diminishing 
their  arcs  in  the  ratio  of  the  square  roots  of  the  motive 
weight. 


THE    MODERN    CLOCK.  47I 

To  accomplish  the  foregoing  conditions,  there  is  but  one 
fixed  point  or  Hne  of  distance  between  the  axis  of  the 
escape  wheel  and  that  of  the  pallet,  and  that  depends  upon 
the  number  of  teeth  embraced  by  the  pallets  and  only  one 
point  in  which  the  pallet  axis  can  be  placed  from  which  the 
several  lines  of  the  escapement  can  be  correctly  traced  and 
properly  constructed  with  equal  angles,  and  equal  rectangu- 
lar lockings  on  both  sides,  so  that  each  part  travels  with 
the  same  degree  of  angular  velocity,  which  are  the  three 
essential  points  of  the  escapement. 

Much  difference  of  opinion  has  been  expressed  upon  the 
construction  of  the  pallets,  as  to  whether  the  lockings  or 
circular  rests  should  be  at  equal  distances  from  the  pallet 
axis,  with  arms  and  impulse  planes  of  unequal  length,  or 
at  unequal  distances  from  the  pallet  axis,  with  arms  and  im- 
pulse planes  of  equal  length.  In  the  latter  case  the  locking 
on  one  side  is  three  degrees  above,  and  on  the  other  three 
degrees  below  the  rectangle,  whereas  in  the  former  the  tooth 
on  both  sides  reposes  at  right  angles  to  the  line  of  pressure; 
but  the  length  of  the  impulse  planes  is  unequal.  When  an 
escapement  is  correctly  made  upon  either  plan,  the  results 
are  very  similar. 

It  is  possible  to  obtain  equal  angles  by  a  false  center  of 
motion  or  pallet  axis ;  but  then  the  arcs  of  repose  will  not 
be  equal.  This,  however,  is  not  of  so  much  consequence  as 
that  of  having  destroyed  the  conditions  Nos.  2,  3,  4;  for 
even  at  correct  centers,  if  the  angles  are  not  drawn  off  cor- 
rectly by  the  protractor,  and  precisely  equal  to  each  other, 
the  isochronous  vibrations  of  the  pendulum  will  be  destroy- 
ed, and  unequal  arcs  will  no  longer  be  performed  in  equal 
times ;  the  quiescent  point  is  not  the  center  of  the  vibration, 
except  when  the  driving  forces  are  equal  on  both  sides  of 
the  natural  quiescent  point  of  the  pendulum  at  rest. 

Now  this  is  the  very  pith  of  the  subject,  and  which  few- 
would  be  inclined  to  look  for  with  any  hope  of  finding  in 


472  THE    MODERN    CLOCK. 

it  the  solution  of  this  important  question,  the  isochronism 
of  the  pendulum. 

-  One  would  naturally  suppose  that  unequal  arcs  on  the 
two  sides  of  the  vertical  lines  would  not  seriously  affect  the 
rate  of  the  clock,  but  would  be  equal  and  contrary,  and  con- 
sequently a  balance  of  errors,  and  so  they  probably  are  for 
the  same  fixed  vibration,  but  not  for  any  other;  because 
dififerent  angles  are  driven  with  different  velocities,  the 
short  angle  has  a  quicker  rate  of  motion  than  the  long. 
Five  pounds  motive  weight  will  multiply  three  times  the 
pendulum's  vibration  over  an  arc  of  escapement  of  0.75°; 
but  the  same  pendulum,  with  an  arc  of  escapement  of  1°, 
would  require  11.20  lbs.  to  treble  its  vibration;  the  times  of 
the  vibration  vary  in  the  same  ratio  as  the  sum  of  the 
squares  of  the  differences  of  the  angles  of  each  pallet,  com- 
pared with  the  spaces  passed  over. 

From  this  it  will  be  seen  that  the  exact  bending  point  of 
the  pendulum  spring  should  be  opposite  the  axis  of  the 
fork  arbor  when  regulating  the  clock  and  this  may  have 
to  be  determined  by  trial,  raising  or  lowering  the  plates  by 
screws  in  the  arms  of  the  suspending  brackets  until  the 
proper  position  is  found,  when  the  movement  may  be 
clamped  firmly  in  position  by  the  binding  screws,  see  Fig. 

158. 

On  common  clocks  the  crutch  is  simply  riveted  on  its 
collet  and  bent  as  required  to  set  the  clock  in  beat,  but  for 
a  first-class  clock  a  more  refined  arrangement  is  usually 
adopted.  There  are  other  plans,  but  perhaps  none  so  thor- 
oughly sound  and  convenient  as  the  following.  The  crutch 
itself  is  made  of  a  piece  of  flat  steel  cut  away  so  as  to  leave 
a  round  boss  at  the  bottom  for  the  fork,  and  a  round  boss 
at  the  top  to  fit  on  a  collet  on  the  pallet  arbor,  a  part  pro- 
jecting above  to  be  embraced  between  a  pair  of  opposing 
screws.  On  the  collet  is  fixed  a  thin  brass  plate  with  two 
lugs  projecting  backwards  from  the  frame,  these  lugs  be- 
ing drilled  and  tapped  to  receive  the  opposing  screws  in  a 


THE    MODERN     CLOCK.  473 

line.  The  boss  of  the  crutch  Hes  flat  against  this  plate,  and 
is  held  up  to  it  by, a  removable  collet.  The  collet  may  be 
pinned  across  or  fitted  keyhole  fashion,  in  either  case  so  as 
to  hold  the  crutch  firmly,  allowing  it  to  move  with  a  little 
stiffness  under  the  influence  of  the  screws.  With  this  ar- 
rangement the  adjustment  to  beat  may  be  made  with  the 
utmost  delicacy  by  slacking  one  screw  and  advancing  the 
other,  taking  care  that  in  the  end  they  are  well  set  home  so 
as  to  make  the  crutch  practically  all  one  piece  with  the 
arbor.  Milled  heads  are  most  convenient  for  these  screws, 
and  being  placed  at  the  top  they  are  easily  got  at.  The 
crutch  should  always  be  fitted  with  a  fork  to  embrace  the 
pendulum  rod,  as  this  ensures  the  impulse  being  given  di- 
rectly through  the  center,  and  with  the  same  object  the  act- 
ing sides  of  the  fork  should  be  truly  square  to  the  frame. 
A  slot  in  the  pendulum  rod  with  a  pin  acting  in  it  is  never 
so  sure  of  being  correct,  as,  although  the  surfaces  may  be 
rounded,  it  is  very  unlikely  that  the  points*of  contact  will 
be  truly  in  the  plane  of  the  axis  of  the  rod.  The  slightest 
error  in  this  respect  will  tend  to  cause  wobbling  of  the  bob, 
although,  to  avoid  this,  great  attention  must  also  be  given 
to  the  suspension  spring,  the  pin  on  which  it  hangs,  and  the 
pin  and  the  hole  at  the  top  of  the  pendulum  rod.  All  these 
points  must  be  in  a  true  line,  and  the  spring  symmetrical  on 
both  sides  of  the  line  in  order  that  the  impulse  may  be  given 
exactly  opposite  the  center  of  the  mass,  otherwise  wobbling 
must  occur,  although  perhaps  of  an  amount  so  small  as  to 
be  difficult  of  detection,  and  this  is  not  a  matter"  of  small  im- 
portance, as  it  has  an  efifect  on  the  rate  which  could  be 
mathematically   demonstrated. 

The  frames  of  many  regulators  are  made  too  large  and 
heavy.  In  some  cases  there  may  be  good  reasons  for  mak- 
ing them  large  and  heavy,  but  in  most  instances,  and  espe- 
cially when  the  pendulum  is  not  suspended  from  the  move- 
ment, it  would  be  much  better  to  make  the  frames  lighter 
than  we  frequently  find  them.     Very  large  frames  present 


474  THE    MODERN    CLOCK. 

a  massive  appearance,  and  convey  an  idea  of  strength  alto- 
gether out  of  proportion  to  the  work  a  regulator  is  required 
to  perform.  They  are  more  difficult  and  more  expensive  to 
make  than  lighter  ones,  and  after  they  are  made  they  are 
more  troublesome  to  handle,  and  the  pivots  of  the  pinions 
are  in  greater  danger  of  being  broken  when  the  clock  is  be- 
ing put  together  than  when  they  are  moderately  light. 

In  a  clock  such  as  we  have  under  consideration,  where 
the  frame  is  not  to  be  used  as  a  support  for  the  pendulum, 
but  simply  to  contain  the  various  parts  which  constitute  the 
movement,  the  thickness  of  the  frames  may  with  propriety 
be  determined  on  the  basis  of  the  diameter  of  the  majority 
of  the  pivots  which  work  into  the  holes  of  the  frames.  The 
length  of  the  bearing  surface  of  a  pivot  will,  according  to 
circumstances,  vary  from  one  to  two  and  a  half  times  the 
diameter  of  the  pivot.  The  majority  of  the  pivots  of  our 
regulator  will  not  be  more  than  .05  or  .06  of  an  inch  in 
diameter;  consequently  a  frame  0.15  of  an  inch  thick  will 
allow  a  sufficient  length  of  bearing  for  the  greater  portion 
of  the  pivots,  and  will  also  allow  for  countersinks  to  be 
made  for  the  purpose  of  holding  the  oil.  If  thin  plates  are 
used  one  or  two  of  the  larger  pivots  should  be  run  in  bushes 
placed  in  the  frame,  as  described  in  Fig.  155. 

The  length  and  breadth  of  the  frame,  and  also  its  shape, 
should  be  determined  solely  on  the  basis  of  utility.  There 
can  be  no  better  shape  for  the  purpose  of  a  regulator  than 
a  plain  oblong,  without  any  attempt  whatever  at  ornament. 
For  our  regulator  a  frame  nine  inches  long  and  seven  inches 
broad  will  allow  ample  accommodation  for  everything,  as 
may  be  seen  on  referring  to  Fig.  157. 

The  plates  are  made  of  various  alloys :  cast-brass,  nickel- 
silver,  and  hard-rolled  sheet-brass.  It  is  difficult  to  make 
plates  of  cast-brass  which  would  be  even,  free  from  specks, 
etc.,  but  cast  plates  may  very  well  be  made  of  ornamental 
patterns  and  bushings  of  brass  rod  inserted,  or  they  may 
be  jeweled  as  shown  in  Figs.  154,   155,  156.     Nickel,  or 


THE    MODERN    CLOCK, 


475 


German  silver,  makes  a  fine  plate,  but  it  is  difficult  to  drill 
the  small  holes  through  plates  of  four-tenths  of  an  inch  in 
thickness,  on  account  of  the  peculiar  toughness  of  the  metal, 
so  that  bushings  are  necessary.  The  best  material  where 
the  holes  are  to  be  In  the  plates  Is  fine,  hard-rolled  sheet 
brass;  it  should  have  about  4  oz.  of  lead  to  the  100  lbs., 
which  will  make  it  "chip  free,"  as  clockmakers  term  it, 
rendering  it  easy  to  drill ;  the  metal  is  so  fine  and  condensed 
to  that  extent  by  rolling,  that  the  holes  can  be  made  with 
the  greatest  degree  of  perfection.  The  many  improvements 
in  tools  and  machinery  have  effected  great  changes  and  im- 
provements in  clock-making.  It  once  was  quite  a  difficult 
task  to  drill  the  small  holes  in  the  plates  with  the  ordinary 
drills  and  lathes ;  now  we  lay  the  plates  "after  they  are  sold- 


I     rniLiMK     I 


^i^^i  A 


Fig.  154 

ered  together  at  the  edges  (which  is  preferable  to  pinning)', 
on  the  table  of  an  upright  drill,  and  with  one  of  the  modern 
twist-drills  the  task  Is  rendered  a  very  easy  one.  After  the 
pivot-holes  are  drilled-,  we  run  through  from  each  side  a 
round  broach,  finished  lengthwise  and  hardened,  which  acts 
as  a  fine  reamer,  straightening  and  polishing  the  holes  ex-' 
quisitely.  A  little  oil  should  be  used  on  the  reamer  to  prevent 
sticking.  The  method  of  fitting  up  the  pivot-holes  invented 
by  LeRoy,  a  French  clockmaker  of  some  note,  is  shown  in 
Fig.  154.  It  is  a  sectional  view  of  the  plate  at  the  pivot- 
hole.  It  will  be  observed  that.  Instead  of  countersinking 
for  the  oil,  the  reverse  is  the  case.  A  is  a  hardened  steel 
plate  counterbored  into  the  clock  plate  B,  and  held  In  its 
place  by  the  screws.  There  should  be  a  small  space  between 
the  steel  plate  and  the  crown  of  the  arch  for  the  oil.  After 
the  clock  has  been  put  together  it  Is  laid  down  on  its  face 


476 


THE    MODERN    CLOCK. 


or  side,  a  drop  of  oil  is  put  to  the  pivot  end,  and  the  steel 
plate  immediately  put  on;  and  the  oil  will  at  once  assume 
the-  shape  of  the  shaded  spot  in  the  drawing,  being  held  in 
the  position  at  the  center  of  the  pivot  by  capillary  attraction, 
until  it  is  exhausted  by  the  pivots;  the  steel  plates  also 
govern  the  end  play  of  the  pinions.  The  pivot  ends  being 
allowed  to  touch  the  plates  occasionally,  the  shoulders  of  the 
pinions  are  turned  away  into  a  curve,  and,  of  course,  do  not 
bear  against  the  plate,  as  in  most  clocks. 


Fig.  155 


Glass  plates  may  be  used  instead  of  steel,  or  rose  cut  thin 
garnets,  or  sapphires,  with  the  flat  sides  smoothly  polished, 
may  be  bought  of  material  dealers  and  set  in  bezels  like  a 
cap  jewel.     They  are  very  hard  and  smooth  for  the  pivot 


Fig.  156 


ends,  and  the  state  of  the  oil  at  the  pivots  can  be  seen  at  any 
time.  Clocks  fitted  up  in  this  manner  have  been  running 
many  years  without  oiling. 

When  fitted  up  in  this  way  the  plates  may  be  thicker. 
We  have  made  the  clock  plates  about  four-tenths  of  an  inch 
in  thickness,  which  allows  of  counterboring,  and  admits  of 
long  bearings  for  the  barrel  arbor,  which  are  so  liable  to  be 
worn  down  in  the  holes  by  the  weights ;  and  the  pivots  of 
the  pinions,  by  being  a  little  longer,  do  not  materially  in- 
crease the  friction. 


THE    MODERN    CLOCK.  477 

In  first-class  clocks,  when  all  the  materials  are  as  hard 
as  possible,  the  wheels  and  pinions  high  numbered,  the 
teeth,  pinions,  pivots,  and  holes  smooth,  true,  and  well  pol- 
ished, the  amount  of  wear  Is  very  slight,  especially  if  the 
driving  weight  has  no  useless  excess.  Yet  there  are  ad- 
vantages in  having  some  parts  jeweled,  such  as  the  pallets 
and  the  four  escapement  holes.  The  cost  of  sufli  jeweling 
is  not  an  objection,  while  the  diminished  friction  of  the 
smooth,  hard  surfaces  is  worth  the  extra  outlay.  The  holes 
can  be  set  in  the  bushes  described  in  Fig.  156,  the  end 
stones  being  cheap  semi-precious  stones,  either  rose  cut  or 
round. 

For  jeweling  the  pallets,  dovetailed  slots  may  be  made  so 
that  the  stones  will  be  of  a  wedge  shape;  there  is  no  need 
for  cutting  the  slots  right  through  as  in  lever  watch  pallets. 
The  stones  will  be  held  more  firmly  if  shaped  as  wedges 
lying  on  a  bed  of  the  steel  and  exposing  only  the  circular 
resting-  curve  and  the  driving  face.  The  slots  can  be  filed 
out  and  the  stones  ground  on  a  copper  lap  to  fit,  fixed  with 
shellac  and  pressed  firmly  home  while  warm.  The  grind- 
ing and  polishin^^  of  the  acting  suriaces  are  done  exactly  as 
described  for  hard  steel,  only  using  diamond  powder  instead 
of  emery.  The  best  stones  are  pale  milky  sapphires,  such 
as  are  useless  as  gems,  this  kind  of  stone  being  the  hardest. 

The  holes  may  be  much  shorter  when  jeweled,  as  the 
amount  of  bearing  surface  required  with  stones  is  less 
than  with  brass;  this  results  in  less  adhesion  through  the 
oil,  and  less  variation  of  force  through  its  changes  of  con- 
sistency. The  'scape  wheel  may  also  be  thinner  w^th  similar 
results,  and  less  weight  to  be  moved  besides.  So  the  advan- 
tages of  jeweling  are  worth  consideration. 

It  is  important  to  finish  the  wheels  and  pinions  before 
drilling  any  holes  in  the  plates  and  then  to  definitely  locate 
the  holes  after  trial  in  the  depthing  tool. 

For  the  clockmaker's  use  the  next  in  value  to  the  wheel- 
cutting  engine  is  a  strong  and  rigid  depthing  tool,  for  it  is 


478  THE    MODERN    CLOCK. 

by  means  of  this  instrument  that  the  proper  center  distances 
of  wheels  and  pinions  can  be  ascertained,  and  all  errors  in 
sizes  of  wheels  and  pinions,  and  shapes  of  teeth,  are  at  once 
detected  before  the  holes  are  drilled  in  the  plates.  In  fact, 
this  tool  becomes  for  the  moment  the  clock  itself ;  and  if 
the  workman  will  consider  that  as  the  wheels  and  pinions 
perform  fh  the  tool  for  the  little  time  he  is  testing  them,  so 
they  will  continue  to  run  during  the  life  of  the  clock,  he 
will  not  be  too  hasty  in  allowing  wheels  to  go  as  correct 
when  a  hundredth  of  an  inch  larger  or  smaller,  and  another 
test,  would,  perhaps,  make  the  pitching  perfect. 

There  are  various  kinds  of  depthing  tools  in  use,  but 
many  of  them  are  objectionable  for  the  reason  that  the  cen- 
ters are  so  long  that  the  marking  points  on  their  outer  ends, 
are  too  far  from  the  point  where  the  pitching  or  depthing 
is  being  tested,  and  the  slightest  error  in  the  parallelism  of 
these  centers  is,  of  course,  multipHed  by  the  distance,  so 
that  it  m.ay  be  a  serious  difference.  Having  experienced 
some  trouble  from  this  cause,  we  made  an  instrument  with 
very  short  centers,  on  the  principle  that  the  marking  points, 
or  centers,  should  be  as  near  the  testing  place  as  possible. 
We  succeeded  in  making  one  with  a  difference  of  only 
three-fourths  of  an  inch,  which  was  so  exact  that  we  had 
no  further  trouble.  It  was  made  on  the  Sector  plan,  but 
upright,  so  that  the  work  under  inspection,  whether  wheels 
and  pinions,  or  escapements,  could  be  observed  closely,  and 
with  a  glass,  if  necessary. 

It  is  very  important  that  the  posts  or  pillars  and  side- 
plates  of  clocks  should  be  m.ade  and  put  together  in  the 
most  thorough  manner ;  the  posts  should  be  turned  exact  to 
length  and  have  large  shoulders,  turned  true,  so  that  the 
plates,  when  put  together  without  screws  should  fit  accur- 
ately, for  if  they  do  not,  when  the  screws  are  driven,  some 
of  the  pivots  will  be  cramped.  We  prefer  iron  for  the 
posts,  it  being  stiffer,  and  better  retaining  the  screw  threads 
in  the  ends,  which  in  brass  are  liable  to  strip  unless  long 


I      bc 


480 


THE    MODERN    CLOCK. 


and  deep  holes  are  tapped.  Steel  pillars  should  be  blued 
after  being  finely  finished,  thus  presenting  a  pleasing  con- 
trast. The  plate  screws  should  also  be  of  steel,  with  large 
flat  heads,  turned  up  true,  and  having  a  washer  next  to  the 
plate.  Brass  pillars  are  favored  by  many  and  are  easier 
turned  in  a  small  lathe,  but  they  should  be  much  larger 
than  the  steel  ones. 

When  the  pillars  are  made  of  brass  round  rod  of  proper 
diameter  is  the  best  stock.  If  this  cannot  be  procured,  a 
pattern  is  turned  from  wood,  and  a  little  larger  in  every 
respect  than  the  pillar  is  desired  to  be.  If  there  is  to  be 
any  ornament  put  on  the  pillar,  it  is  never  made  on  the  pat- 
tern, because  it  makes  it  more  difficult  to  cast,  and  besides, 
the  ornamentation  would  all  be  spoiled  in  the  hammering. 
The  pattern  must  be  turned  smooth,  and  the  finer  it  is  the 
better  w^ill  be  the  casting.    After  the  casting  is  received  the 


":> 


Fig.  159 


first  thing  to  be  done  is  to  hammer  the  brass,  and  then  cen- 
ter the  holes,  because  it  will  be  seen  from  Fig.  159  that 
there  are  holes  for  screws  at  each  end  of  the  pillar.  Holes 
of  about  .20  of  an  inch  are  then  bored  in  the  ends  of  the 
pillars,  and  should  be  deep,  because  deep  holes  do  no  harm 
and  greatly  facilitate  the  tapping  for  the  screws.  After  the 
holes  are  tapped,  run  In  a  bottoming  tap  and  then  counter- 
sink them  a  little,  to  prevent  the  pillar  from  going  out  of 
truth  in  the  turning.  It  will  depend  a  great  deal  on  the 
conveniences  which  belong  to  the  lathe  the  pillars  are  turn- 
ed in  as  to  how  they  will  be  held  in  the  lathe  and  turned. 
If  the  holes  in  the  ends  of  the  pillars  have  been  bored  and 
tapped  true,  and  if  the  lathe  has  no  kind  of  a  chuck  or 
face  plate  with  dogs,  suitable  for  holding  rods,  the  best 


THE    MODERN    CLOCK.  481 

way  IS  to  catch  a  piece  of  stout  steel  wire  in  the  chuck  and 
turn  it  true,  cut  a  true  screw  on  it,  and  on  this  screw  one 
end  of  the  pillar,  and  run  the  other  end  in  a  male  center. 
However,  if  the  screws  are  not  all  perfectly  true,  and  the 
centers  of  the  lathe  not  perfectly  in  line,  this  plan  will  not 
work  well,  and  it  will  be  necessary  to  catch  a  carrier  on  to 
the  pillar  and  turn  it  between  two  male  centers. 

The  dial  feet  are  precisely  the  same  as  the  pillars,  only 
smaller.  These  dial  feet  are  intended  to  be  fastened  in  the 
frame  by  a  screw,  the  same  as  the  pillars ;  but  it  will  be  ob- 
served that  the  screw  which  is  intended  to  hold  the  dial  on 
the  pillar  is  smaller.  The  dial  feet  will  be  turned  in  precise- 
ly the  same  manner  as  the  pillars.  For  finishing  the  plain 
surfaces  of  the  pillars  and  dial  feet,  an  old  6  or  7-inch 
smooth  file  makes  a  good  tool  The  end  of  the  file  is  ground 
flat,  square  or  slightly  rounded,  and  perfectly  smooth.  The 
smoother  the  cutting  surface  the  smoother  the  work  done 
by  it  will  be.  It  is  difficult  to  convey  the  idea  to  the  inex- 
perienced how  to  use  this  tool  successfully.  In  the  first 
place,  a  good  lathe  is  necessary,  or  at  least  one  that  allows 
the  work  to  run  free  without  any  shake.  In  the  second 
place,  the  tool  must  be  ground  perfectly  square,  that  is,  it  is 
not  to  be  ground  at  an  angle  like  an  ordinary  cutting  tool. 
Then  the  rest  of  the  lathe  must  be  smooth  on  the  top,  and 
the  operator  must  have  confidence  in  himself,  because  if  he 
thinks  that  he  cannot  turn  perfectly  smooth,  it  will  be  a  long 
time  before  he  is  able  to  do  it.  A  tool  for  turning  the 
rounded  part  of  the  pillar,  if  a  pattern  of  this  style  is  de- 
cided on,  is  made  by  boring  a  hole,  the  size  of  the  desired 
curve,  in  an  old  file,  or  in  a  piece  of  flat  steel,  and  smooth- 
ing the  hole  with  a  broach  and  then  filing  away  the  steel. 
The  shoulders  should  be  smooth  and  flat,  or  a  very  little 
undercut,  and  the  ends  of  the  pillars  should  be  rounded  as 
is  shown  in  Fig.  159,  because  rounded  points  assist  greatly 
in  making  the  frames  go  on  to  the  pillars  sure  and  easy, 
and  greatly  lessen  the  danger  of  breaking  a  pivot  when  the 
clock  is  being  put  together. 


482  THE    MODERN    CLOCK. 

When  a  washer  is  used  the  points  of  the  pillars  project 
half  the  thickness  of  the  washer  through  the  frames,  the 
hole  in  the  washer  being  large  enough  to  go  on  to  the 
points  of  the  pillars. 

Figure  160  is  an  outline  of  the  cock  required  for  the  pal- 
let arbor,  and  the  only  cock  that  will  be  required  for  the 
regulator.  It  is  customary,  in  some  instances,  to  use  a 
cock  for  the  scape-wheel  and  also  for  the  hour-wheel  arbors, 


Fig.  160 

but  for  the  scape-wheel  arbor  I  consider  that  a  cock  should 
never  be  used  when  it  can  be  avoided.  The  idea  of  using 
a  cock  for  the  scape-wheel  arbor  is  to  bring  the  shoulder 
of  the  pivot  near  to  the  dial  and  thereby  make  the  small 
pivot  that  carries  the  seconds  hand  so  much  shorter;  and 
so  far  this  is  good,  but  then  the  distance  between  the  shoul- 
ders of  the  arbor  being  greater,  when  a  cock  is  used  the 
arbor  is  more  liable  to  spring  and  cause  the  scape-wheel  to 
impart  an  irregular  force  to  the  pendulum  through  the  pal- 
lets. This  is  the  reason  why  I  prefer  not  to  use  a  cock 
except  when  the  design  of  the  case  is  such  that  long  dial 
feet  are  necessary,' and  renders  the  use  of  a  cock  indispen- 
sable. In  the  present  instance,  however,  the  dial  feet  are 
no  longer  than  is  just  necessary  to  allow  for  a  winding 
square  on  the  barrel  arbor,  and  therefore  a  cock  for  the 
scape  wheel  is  superfluous.  It  is  better  to  use  a  long  light 
socket  for  the  seconds  hand  than  put  a  cock  on  the  scape- 
wheel  arbor  in  ordinary  cases.  Except  for  the  purpose  of 
uniformity  a  cock  on  the  hour  wheel  is  always  superfluous, 
although  its  presence  is  comparatively  harmless.  The  front 
pivot  of  the  hour-wheel  axis  can  always  be  left  thick  and 


THE    MODERN    CLOCK.  483 

Strong  enough  should  the  design  of  the  case  require  the  dial 
feet  to  be  extra  long. 

For  the  pallet  arbor,  however,  a  cock  is  always  necessary, 
and  it  should  always  be  made  high  enough  to  allow  the 
back  fork  to  be  brought  as  near  to  the  pendulum  as  possi- 
ble, so  as  to  prevent  any  possibility  of  its  twisting  when 
the  power  is  being  communicated  from  the  pallets  to  the 
pendulum.  This  cock  should  be  made  about  the  same  thick- 
ness as  the  frames,  and  about  half  an  inch  broad.  ]\Iake  the 
pattern  out  of  a  piece  of  hard  wood,  either  in  one  solid 
piece  or  by  fastening  a  number  of  pieces  together.  The 
pattern  should  be  made  a  little  heavier  than  the  cock  is  re- 
quired to  be  when  finished,  and  it  should  also  be  made 
slightly  bevelled  to  allow  it  to  be  easily  drawn  from  the 
sand  when  preparing  the  mould  for  casting.  After  it  is 
cast  the  brass  should  be  hammered  carefully,  and  then  filed 
square,  flat,  and  smooth. 

Screws  are  better  and  cheaper  when  purchased,  but  they 
may  be  made  of  steel  or  brass  rod  by  any  workman  who  is 
provided  with  a  set  of  fine  taps  and  dies.  If  purchased  thev 
should  be  hardened,  polished  and  blued  before  using  them 
in  the  regulator.  The  threads  of  screws  vary  in  proportion 
to  the  size  of  the  screw  and  the  material  from  which  it  is 
made.  A  screw  with  from  32  to  40  turns  to  the  inch,  and  a 
thread  of  the  same  shape  as  the  fine  dies  for  sale  in  the  tool 
shops  make,  is  well  adapted  for  the  large  screws  in  a  regu- 
lator. However,  it  is  not  threads  of  the  screws  I  desire  to 
call  attention  to  so  much,  although  it  must  be  admitted  that 
the  threads  are  of  primary  importance.  It  is  the  shape  of 
the  heads  and  the  points  which  is  too  often  neglected. 

A  thread,  or  a  thread  and  a  half,  cut  down  on  the  point 
of  a  screw,  will  allow  it  to  enter  easier  than  when  the  point 
is  flat,  round,  or  shaped  like  a  center.  This  is  not  a  new 
idea  for  making  the  points  of  screws,  but  the  plan  is  either 
not  known  to  many,  or  it  is  not  practiced  to  the  extent  it 
ought  to  be. 


484  THE    MODERN    CLOCK. 

The  shape  of  the  head  of  a  screw  should  also  always  be 
based  on  utility,  and  the  shape  that  will  admit  of  a  slit  into 
it  that  will  wear  well  should  be  selected.  A  round  head 
ought  never  to  be  used,  because  a  head  of  thit  shape  does 
not  present  the  same  amount  of  surface  to  the  screwdriver 
that  a  square  head  does.  It  is  the  extreme  end  of  the  slit 
that  is  most  effective,  and  in  round-headed  screws  this  part 
is  cut  away  and  the  value  of  the  head  for  wearing  by  the 
use  of  the  screwdriver  is  the  same  as  if  the  head  of  the 
screw  was  so  much  smaller.  A  chamfered  head  may  suit 
the  tastes  of  some  people  better  than  a  perfectly  flat  head, 
but  in  a  head  of  this  shape  the  slit  must  be  cut  deeper  than 
in  a  square  head,  because  the  chamfered  part  of  the  head  is 
of  little  or  no  use  for  the  screwdriver  to  act  against.  The 
slits  should  always  be  cut  carefully  in  the  center  of  the  head 
and  the  sides  of  the  slit  filed  perfectly  flat  with  a  thin  file 
and  the  slight  burr  filed  off  the  edge  to  prevent  the  top  of 
the  head  getting  bruised  by  the  action  of  the  screwdriver. 
The  shape  of  the  slit  which  is  best  adapted  for  wearing  is 
one  slightly  tapered,  with  a  round  bottom.  The  round  bot- 
tom gives  greater  strength  to  the  head,  and  prevents  the 
heads  of  small  screws  from  splitting. 

I  have  dwelt  at  some  length  on  these  little  details  because 
a  proper  attention  to  them  goes  a  long  way  in  the  making 
of  a  clock  in  a  workmanlike  manner,  and  it  is  desirable  that 
the  practical  details  should  be  as  minute  as  possible. 

The  construction  of  the  barrel  is  a  subject  which  requires 
a  greater  amount  of  consideration  than  is  sometimes  be- 
stowed upon  it.  We  often  meet  with  regulator  barrels 
which  have  considerable  more  brass  put  into  them  than  is 
necessary.  The  value  of  this  extra  metal  is  of  little  or  no 
consequence.  It  is  the  unnecessary  pressure  the  weight  of 
it  causes  on  the  barrel  pivots,  and  the  consequent  increase 
of  friction,  which  is  objectionable.  For  this  reason  the 
weight  of  the  barrel,  as  v^ell  as  the  weight  of  every  other 
part  of  the  clock  that  moves  on  pivots,  should  be  made  no 


THE    MODERN    CLOCK, 


485 


heavier  than  is  absohitely  necessary  to  secure  the  required 
amount  of  strength.  In  every,  instance,  except  when  the 
diameter  is  required  to  be  very  small,  the  barrel  should  be 
made  of  a  piece  of  thin  brass  tubing  with  two  ends  of  cast 
brass  fastened  into  it. 

Figure  161  is  a  sectional  view  of  the  ends  of  a  barrel; 
the  diagram  on  the  right  is  the  end  where  the  great  wheels 
rest  against,  and  the  one  on  the  left  is  the  other  end.  The 
insides  of  both  these  ends  are  precisely  the  same,  but  the 
outsides  differ  a  little.     It  will  be  observed  that  there  is  a 


Fig.  161 


little  projection  near  the  hole  on  the  outside  of  the  front 
end.  This  projection  is  left  with  the  view  of  making  the 
hole  in  the  center  longer,  and  thereby  causing  this  end  to 
take  a  firmer  hold  on  the  barrel  arbor.  The  back  end,  or 
the  end  that  the  great  wh'eels  rest  against,  and  where  the 
ratchet  teeth  are  cut,  is  shaped  precisely  like  the  diagram 
on  the  right  of  Fig.  161.  If  you  cannot  get  brass  plate  of 
sufficient  thickness  for  the  ends  of  the  barrel  they  must  be 
cast. 

The  patterns  for  these  barrel  ends  should  be  made  with- 
out any  hole  in  the  center,  and  in  every  way  heavier  and 
thicker  than  they  are  to  be  when  finished,  because  it  is  diffi- 
cult to  obtain  good  and  solid  castings  when  the  patterns  are 
made  thin,  although  it  is  by  no  means  impossible  to  make 
them  so.  Like  all  brass  castings  used  for  the  clockmaker's 
purpose,  they  should  be  carefully  hammered,  and,  although 
these  pieces  are  of  an  Irregular  shape,  they  can  be  easily 


486  THE    MODERN    CLOCK. 

hammered  regularly  with  the  aid  of  narrow-faced  hammers 
or  punches,  and  with  the  exercise  of  a  little  patience.  After 
hammering,  the  castings  should  be  placed  on  a  face  plate 
in  the  lathe,  and  the  tube  which  is  to  form  the  top  part  of 
the  barrel  fitted  easy  and  without  shake  on  to  the  flanges 
and  the  other  parts  of  the  castings  turned  down  to  the  re- 
quired thickness,  and  a  hole  a  little  less  than  0.3  of  an  inch 
diameter  bored  in  the  center  of  each  before  it  is  removed 
from  the  face  plate.  The  tube  which  is  to  form  the  top  of 
the  barrel  should  be  no  heavier  than  is  just  necessary  to  cut 
a  groove  for  the  cord,  and  for  this  regulator  it  should  be  1.5 
inch  diameter  outside  measurement,  1.5  inch  long,  and  turn- 
ed perfectly  true  on  the  ends. 

The  hole  in  the  front  end  of  the  barrel,  which  is  the  end 
nearest  to  the  dial,  should  be  broached  a  little  from  the  in- 
side, and  the  other  end  broached  a  little  larger  from  the  out- 
side. The  reason  for  broaching  the  holes  in  this  manner  is 
to  cause  the  thickest  part  of  the  barrel  arbor  to  be  at  the 
place  where  the  great  wheels  work,  because,  in  making  a 
barrel  for  a  regulator,  it  will  generally  be  found  that  the 
arbor  requires  to  be  thickest  in  this  particular  place.  The 
arbor  should  be  made  from  a  piece  of  fine  cast  steel  a  little 
more  than  0.3  of  an  inch  thick,  and  not  less  than  four  inches 
long.  It  is  always  well  to  have  the  steel  long  enough.  This 
steel  should  be  carefully  centered  and  turned  true,  and  of 
the  same  size  and  taper  as  the  holes  in  the  barrel  ends.  It 
is  not  necessary  that  the  barrel  arbor  should  be  hardened 
and  tempered,  except  on  special  occasions.  In  most  cases 
it  will  last  as  long  as  any  other  part  of  the  clock  if  it  is  left 
soft,  and  it  is  much  easier  to  make  when  soft.  Before  fit- 
ting the  arbor  to  the  barrel  ends  it  is  well  to  place  the  ends 
into  the  tube  that  is  to  form  the  top  of  the  barrel,  because 
a  better  fit  can  be  made  in  this  way  than  when  each  is  fitted 
separately.  When  the  arbor  has  been  fitted,  a  good  and 
convenient  way  of  fastening  it  together  is,  to  use  soft  solder. 
It  can  be  easily  heated  to  the  required  degree  of  heat  with 


THE    MODERN    CLOCK.  487 

the  blow-pipe.  A  very  little  solder  is  sufficient  for  the  pur- 
pose, and  if  the  joints  have  been  well  fitted  the  solder  will 
not  show  when  the  work  is  finished.  Care  should  be  taken 
to  notice  that  the  solder  adheres  to  the  arbors  properly. 
Perhaps  it  would  be  well  to  mention  here  that,  should  the 
clockmaker  not  have  access  to  a  cutting  engine  with  con- 
veniences attached  to  it  for  cutting  the  barrel  ratchet  after 
the  barrel  has  been  put  together,  the  ratchet  should  be  cut 
first. 

When  the  different  pieces  which  constitute  a  barrel  have 
been  fastened  together  the  brass  work  has  next  to  be  turned 
true,  and  the  grooves  cut  for  the  cord  to  run  in.  It  is  best 
not  to  turn  anything  off  the  arbor  till  the  grooves  are  cut, 
because  they  are  usually  cut  smoother  v/hen  the  arbor  is 
strong.  The  most  important  points  to  notice  when  turning 
a  barrel  is  to  be  sure  that  the  top  is  of  equal  diameter  from 
the  one  end  to  the  other,  and  that  the  bearing  wdiere  the 
great  wheels  rest  against  are  perfectly  true,  because,  if  the 
top  of  a  barrel  is  of  unequal  thickness,  the  weight  will  piill 
with  unequal  force  as  it  runs  down,  and  if  the  bearing  on 
the  end  be  out  of  truth  the  great  w^heels  will  also  be  very 
liable  to  get  out  of  truth,  as  their  position  on  the  barrel  is 
altered  by  winding  the  clock  up. 

The  shape  of  the  outside  of  the  barrel  ends,  as  is  rep- 
resented in  Fig.  161,  will  be  found  to  be  good  and  service- 
able. AA  is  the  bearing  for  the  great  wheels  to  rest  against  ; 
BB  is  where  the  ratchet  teeth  are  to  be  cut.  There  must 
be  a  little  turned  off  the  face  of  BB,  as  is  shown  in  the  dia- 
gram, so  as  to  prevent  the  great  wheel  from  rubbing  on 
the  teeth.  The  space  between  AA  and  the  barrel  arbor  is 
turned  smooth. 

Although  it  is  by  no  means  an  absolute  necessity  to  have 
a  groove  cut  in  the  top  of  the  barrel,  yet  it  is  extremely  de- 
sirable that  there  should  be  one,  so  that  the  cord  may  al- 
ways be  guided  with  certainty  as  the  clock  is  w^ound  up.  It 
has  long  been  a  disputed  question  whether  the  cord  should 


^SS  UiE    I.I  ODE  KM    C1.0CK. 

be  fastened  at  the  front  end  of  the  barrel  and  wind  towards 
the  back,  or  whether  it  should  be  fastened  at  the  back  and 
wind  towards  the  front.  I  am  not  aware  that  there  is  any 
violation  of  principle,  so  far  as  the  regularity  of  the  power 
is  concerned,  whether  the  cord  runs  one  way  or  the  other. 
I  understand  it  to  be  solely  a  question  of  keeping  the  weight 
clear  of  the  case  and  the  pendulum  ball.  In  ordinary  con- 
structed regulator  cases  this  object  will  be  best  attained  by 
cutting  the  screw  so  that  the  cord  can  be  fastened  at  the 
front  of  the  barrel  and  wind  towards  the  back;  because  in 
making  it  in  this  way,  the  weight  is  the  length  of  the  barrel 
farther  away  from  the  front  of  the  case  when  it  is  wound 
up,  and  about  the  same  distance  farther  away  from  the 
pendulum  ball  when  it  is  nearly  run  down,  than  if  the  cord 
was  fastened  at  the  back  end  of  the  barrel  and  wound 
towards  the  front.  The  cutting  of  the  groove  is  usually 
done  in  an  ordinary  screw  cutting  lathe. 

In  making  the  pivots  on  a  barrel  it  is  the  usual  custom  to 
make  the  back  pivot  smaller  than  the  front  one  but,  with 
all  due  respect  for  this  time-honored  custom,  I  would  di- 
rect a  little  attention  to  the  philosophy  of  continuing  to 
make  the  barrel  pivots  of  a  regulator  in  this  manner.  Fric- 
tion varies  with  pressure ;  a  large  pivot  has  a  greater 
amount  of  friction  than  a  smaller  one,  because  the  pressure 
on  the  sliding  surface  of  the  revolving  body  is  farther  away 
from  the  center  of  m.otion  in  one  case  than  in  the  other. 
In  regulators  where  the  barrel  pivots  are  of  a  different  size, 
the  effective  force  of  the  weight  will  vary  slightly  accord- 
ing as  the  weight  is  fully  wound  up  or  nearly  run  down.  In 
one  instance  the  pressure  of  the  weight  is  more  directly  on 
the  large  pivot  than  it  is  on  the  smaller  one;  and  in  the 
other  instance  the  pressure  is  more  directly  on  the  small 
pivot  than  it  is  on  the  larger  one,  and  when  the  weight  is 
half  wound  up,. or  half  run  down,^  the  pressure  is  equal  on 
both  pivots. 


THE    MODERN    CLOCK.  489 

In  the  center  pinion  and  in  some  of  the  other  arbors  of  a 
clock,  it  is  sometimes  necessary  to  make  one  pivot  con- 
siderably larger  than  the  other ;  but  in  these  cases 
the  difference  in  the  size  of  the  pivots  does  not  affect  the 
regularity  of  the  transmission  of  the  power,  because  the 
pressure  that  turns  the  wheel  is  always  at  the  same  point. 
In  a  regulator  barrel,  however,  the  pressure  of  the  cord  and 
weight  shifts  gradually  from  one  end  of  the  barrel  to  the 
other,  as  the  clock  runs  down,  and  when  the  pivots  are  of 
unequal  thickness  the  power  is  transmitted  nearly  as  ir- 
regular as  if  the  top  of  the  barrel  was  slightly  conical  and 
both  pivots  of  the  same  size.  For  the  above  reason,  I  think, 
that  it  will  be  plain  to  all  that  in  a  fine  clock  both  of  the 
barrel  pivots  should  be  made  of  an  equal  diameter.  The 
front  pivot  should  be  made  no  larger  than  is  absolutely  nec- 
essary for  a  winding  square,  and  when  we  take  the  fact  into 
consideration  that  a  fine  clock  with  a  Graham  escapement 
requires  considerable  less  power  to  keep  it  in  motion  than 
an  eight-day  marine  chronometer  does,  we  may  safely  con- 
clude that  the  winding  squares  of  many  regulators  of  the 
Graham  class  might  be  made  smaller.  A  pivot  about  0.2 
of  an  inch  will  secure  a  sufficient  amount  of  strength. 
For  the  reasons  mentioned  above,  the  back  pivot  should  be 
exactly  the  same  diameter,  and  although  the  effects  of  fric- 
tion will  be  slightly  greater  when  both  pivots  are  of  an 
equal  size,  still  the  force  of  the  weight  will  be  transmitted 
more  regularly,  w^hich  is  the  object  aimed  at.  Where  the 
plates  are  bushed  a  length  of  two  to  three  diameters  is  long 
enough  for  the  pivot  holes. 

The  stop  works,  maintaining  powers  and  general  ar- 
rangement of  the  great  wheel,  ratchets  and  clicks,  have 
been  so  fully  described  and  illustrated  on  pages  282  to  290, 
Figs.  83  to  87,  that  it  would  be  useless  duplication  to  re- 
peat them  here,  and  the  reader  is  therefore  referred  to  those 
pages,  for  full  particulars.  This  is  also  the  case  with  the 
purely   mechanical    operations    of   cutting   the   w^heels   and 


490  ThK    MODERN    CLOCK. 

pinions,  hardening,  polishing,  staking,  etc. ;  all  have  been 
fully  treated;  but  there  are  some  further  considerations 
which  may  be  mentioned  here.  The  practical  value  of  mak- 
ing pinions  with  very  high  numbers  is  very  much  over- 
rated. I  know  of  two  clocks  situated  in  the  same  building 
that  are  compared  every  other  day  by  transit  observation. 
They  both  have  Graham  escapements  and  mercurial  pendu- 
lums, and  are  equally  well  fitted  up,  and  as  far  as  the  eye 
can  detect,  they  are  about  equally  well  made  in  all  the  essen- 
tial points,  with  only  this  difference :  one  clock  has  pinions 
of  eight,  and  the  other  pinions  of  sixteen  leaves,  yet  for  two 
years  one  clock  ran  about  equally  as  well  as  the  other.  In 
fact,  if  there  was  any  difference,  it  was  in  favor  of  the  clock 
with  the  eight-leaved  pinions.  In  giving  this  example,  I 
must  not  be  understood  to  be  placing  little  value  on  high- 
numbered  pinions.  I  know  that  in  some  instances  they  can 
be  used  to  advantage.  The  idea  that  I  want  to  illustrate  at 
present  is,  that  it  is  not  in  this  direction  that  we  are  to 
search  for  the  means  of  improving  the  rates  of  regulators. 

A  pinion  as  low  as  eleven  leaves  can  be  made  so  that  the 
action  of  the  tooth  will  begin  at  or  beyond  the  line  of  cen- 
ters; but  as  eleven  is  an  inconvenient  number  to  use  in 
clock-work,  we  may  with  great  propriety  decide  upon 
twelve  as  being  a  sufficient  number  of  leaves  for  all  the 
pinions  used  in  a  regulator  having  a  Graham  escapement. 

In  arranging  the  size  of  the  wheels  in  a  regulator,  the 
diameters  of  the  center  and  third  wheels  are  determined  by 
the  distance  between  the  center  of  the  minute  and  the  cen- 
ter of  the  seconds  hand  circle  on  the  dial.  As  the  dials  of 
regulators  are  usually  engraved  after  the  dial  plates  have 
been  fitted,  and  as  the  position  of  the  holes  in  the  dial  for 
the  center  and  scape  wheel  pivots  to  come  through  deter- 
mines the  size  of  the  seconds  circle,  it  may  be  well  to  men- 
tion here  that,  for  a  twelve-inch  dial,  two  and  a  half  inches 
is  a  good  distance  for  the  center  of  the  minute  circle  to  be 
from  the  center  of  the  seconds  circle.     Consequently  the 


THE    MODERN    CLOCK.  49I 

center  and  third  wheels  must  be  made  of  such  a  diameter 
as  will  raise  the  scape  wheel  arbor  two  and  a  half  inches 
from  the  center  arbor,  and  the  other  wheels  must  be  made 
proportionably  larger,  according  to  the  number  of  teeth  they 
contain. 

We  all  know  what  a  difficult  matter  it  is  to  make  a  cutter 
that  will  cut  a  tooth  of  the  proper  shape ;  but  when  the  cut- 
ter is  once  made  and  carefully  used,  we  also  know  that  it 
will  cut  or  finish  a  great  number  of  wheels  without  injury. 
For  this  reason,  those  who  are  contemplating  making  only 
one,  or  at  most  but  a  few  regulators,  will  find  the  work  will 
be  greatly  simplified  by  making  the  wheels  of  a  diameter 
proportionate  to  the  number  of  teeth  they  contain,  and  for 
all  practical  purposes  the  cutter  that  cuts  or  finishes  the 
teeth  of  one  wheel  will  be  sufficiently  accurate  for  the  oth- 
ers. If  we  make  all  the  pinions  with  the  same  number  of 
leaves  they  will  also  all  be  nearly  of  the  same  diameter,  and 
may  be  cut,  or  rather  the  cutting  operation  may  without 
any  great  impropriety  be  finished  with  one  cutter. 

An  opinion  prevails  among  a  certain  class  of  workmen 
that  the  teeth  of  the  great  wheel  and  leaves  of  the  center 
pinion  should  be  made  larger  and  stronger  than  the  other 
wheels  and  pinions,  because  there  is  a  greater  strain  upon 
them  than  on  the  other.  However  reasonable  this  idea  may 
seem,  a  little  consideration  will  show  that  in  the  case  of  a 
regulator,  with  a  Graham  escapement,  where  so  little  mo- 
tive power  is  required  to  keep  it  in  motion,  an  arrangement 
of  this  nature  is  altogether  unnecessary.  The  smallest  teeth 
ever  used  in  any  class  of  regulators  are  strong  enough  for 
the  great  wheel ;  and  if  there  be  a  greater  amount  of  strain 
on  the  teeth  of  the  great  wheel  in  comparison  with  the  teeth 
of  the  third  wheel,  for  example,  then  make  the  great  wheel 
itself  proportionately  thicker,  as  is  usually  done,  according 
to  the  extra  amount  of  strain  that  it  is  to  bear.  The  teeth 
of  wheels  and  the  leaves  of  pinions  wear  more  from  imper- 
fect construction  than  from  any  want  of  a  sufficient  amount 
of  metal  in  them. 


492  THE    MODERN    CLOCK. 

If  we  assume  the  distance  between  the  center  of  the 
minute  and  the  center  of  the  seconds  circle  to  be  2^ 
inches,  and  also  assume  that  the  clock  will  have  a  seconds 
pendulum,  and  all  the  pinions  have  12  leaves,  and  the  bar- 
rel make  one  turn  in  12  hours,  then^  the  following  is  the 
diameter  the  wheels  will  require  to  be,  so  that  the  teeth 
may  all  be  cut  with  one  cutter,  and  also  the  number  of 
teeth  for  each  wheel: 

Great  wheel  144  teeth.  Diameter  3.40  inches  for  the  pitch 
circumference. 

Hour  wheel  144  teeth.  Diameter  3.40  inches  for  the  pitch 
circumference. 

Center  wheel,  96  teeth.  Diameter  2.26  inches  for  the  pitch 
circumference. 

Third  wheel  90  teeth.  Diameter  2. 11  inches  for  the  pitch 
circumference. 

Scape  wheel  30  teeth.  Diameter  1.75  inches  for  the  pitch 
circumference. 

The  number  of  arms  or  crosses  to  be  put  in  a  wheel  is 
usually  decided  by  the  taste  of  the  person  making  the  clock. 
There  is,  however,  another  view  of  the  subject,  which  I 
would  like  to  mention.  With  the  same  weight  of  metal  a 
wheel  will  be  stronger  with  six  arms  than  with  four  or  five, 
and  as  lightness,  combined  with  strength,  should  be  the  ob- 
ject aimed  at  in  making  wheels,  I  prefer  six  arms  to  four  or 
five  for  the  wheels  of  a  regulator. 

Figs.  157  and  158  are  front  and  side  elevations  of  the 
proposed  regulator  m.ovement,  showing  the  size  and  posi- 
tion of  the  wheels,  the  size  of  the  frames,  the  positions  of 
the  pillars,  dial  feet,  etc.  The  dotted  large  circular  lines 
on  Fig.  157  show  the  position  the  hour,  minutes,  and  sec- 
onds circles  will  occupy  on  the  dial.  According  to  the  ordi- 
nary rules  of  drawing,  the  dotted  lines  would  infer  that  the 
movement  is  in  front  of  the  dial,  and  perhaps  it  may 
be  necessary  to  explain  that  in  the  present  instance  these 


THE    MODERN    CLOCK.  493 

lines  are  made  dotted  solely  with  the  view  of  making  the 
diagram  more  distinct,  and  are  not  intended  to  represent 
the  dial  to  be  at  the  back  of  the  movement.  A  is  the  barrel, 
B  is  the  great  wheel,  which  turns  once  in  twelve  hours; 
C  is  the  hour  wheel,  which  works  into  the  great  wheel,  and 
also  turns  once  in  twelve  hours ;  D  is  the  center  wheel, 
which  turns  once  in  an  hour,  and  carries  the  minute  hand; 
E  is  the  third  wheel,  and  F  is  the  scape  wheel,  which  turns 
once  in  a  minute  and  carries  the  seconds  hand;  G  is  the 
pallets ;  H  the  pillars,  and  I  is  the  dial  feet ;  J  is  the  main- 
taining power  click,  and  K  shows  the  position  of  the  cord. 
Neither  the  hour  or  great  wheels  project  over  the  edge  of 
the  frame,  and  it  will  be  observed  that  a  clock  of  this  ar- 
rangement is  remarkable  for  its  simplicity,  having  only  four 
wheels  and  three  pinions,  with  the  addition  of  the  scape 
wheel  and  the  barrel  ratchets.  There  are  no  motion  or  dial 
wheels,  the  wheel  C  turning  once  in  12  hours,  carrying  the 
hour  hand.  The  size  and  shape  of  the  frames  and  the  posi- 
tion of  the  pillars,  allows  the  dial  feet  to  be  placed  so  that 
the  screws  which  hold  the  dial  will  appear  in  symmetrical 
positions  on  the  dial. 

Formerly  the  term  "astronomical"  was  applied  to  clocks 
which  indicated  the  motions  and  times  of  the  earth,  moon, 
and  other  celestial  bodies,  but  at  present  we  may  take  it 
as  indicating  such  as  are  used  in  astronomical  ob- 
servatories. In  all  essential  particulars  they  are  the 
same  as  first  class  watchmakers'  regulators,  the  most 
obvious  departure  being  that  the  hour  hand  is  made 
to  revolve  only  once  a  day,  the  dial  being  divided  into 
twenty-four  hours.  This  only  requires  an  intermediate 
wheel  and  pinion  in  the  motion  work,  and,  assuming  the 
hour  hand  to  be  driven  from  the  center  arbor,  there  will  be 
the  usual  hour  and  minute  wheels  and  cannon  pinion.  The 
most  suitable  ratio  for  these  are  ^  and  1/6  =  1/24,  and, 
as  any  numbers,  being  multiples,  may  be  used,  they  may  as 
well  be  selected  so  as  to  be  cut  with  the  same  tools  as  the 


494  'T^E    MODERN    CLOCK. 

wheels  of  the  train.  Two  pinions  of  20  and  wheels  of  80 
and  120  suit  very  well ;  20  -f-  80  and  20  -f-  120  =  20/80  X 
20/120  =  400/9600  =  1/24,  and  the  hands  will  both  go  in 
the  same  direction. 

Some  astronomical  clocks  show  mean  solar,  and  others 
sidereal  time;  this  requires  no  structural  alteration,  merely 
a  little  shortening  of  the  pendulum  in  the  latter  case,  which 
can  be  done  with  the  regulating  nut. 


LIST  OF  ILLUSTRATIONS. 


Addendum 202,  218,  220 

Angular  Motion 103,112 

Automatic  Pinion  Cutter  245,  247 

Drill 249 

"            Wheel  and  Pinion 
Cutter... 254 


Calendar,    Simple 351 

"  Perpetual  354,  356,  358 

Center   Distances 105,  111,  202 

Chimes,  Laying   out - 

370,  421,  422,  423,  424,  425 

Chimes  Westminster 372 

Click,  Position  of _..288 

Cock 482 

Compensated  Rod,  Steel  and 

Zinc 42 

Counter-poising  Hands... 443 

Count  hook.  Position  of 305 

Count  Wheel  Striking  Train 

302,  303,  311,  314,  315,  316,  322,  324 
Cuckoo  Bellows  and  Pipe 328 

D 

Dedendum 202 

Dial  Work 295 

Diameters  of  Wheels,  Getting  196 

E 

Eight-day  Count    Wheel,   Time 
and  Striking  Trains  299.. -.309 

Eight-day  Snail  Strike -342 

Electric   Chimes... 

—.421,422,  423,424,425 

Electric  Clocks,  Pendulum 

Driven 377,379,381,382 

Electric  Clocks,  Weight 

Driven 394,  395,  396,398 

Epicycloid 206,  219,  239 


Escape  Wheel,  Cutting.. .122,  121 
"  "         Drawing  to  fit 

Pallets lao 

Escapement,  Anchor 

—  .142,144,145,146,147 
"  Brocot's  Visible 

127,  129 

"  Cylinder.. 

164, 165, 166,  167, 177, 179, 181,  V83 
Dead  Beat    117,  118 

"  Drum 148 

"  Gravity 

152,   154,  157,  159, 161 

Pin 185,  194 

Pin  Wheel  136,  137 

"  Recoil 

142.    144,  145, 146,  147 
to    draw  the 114 

r 

Friction  Springs 294 

G 

Grandfather  clocks S52 

H 

Hypocycloid 206 

K 

Keyhole  Plates 289 


Lever  Escapement  for  Clocks  193 
Levers,  the  Elements  of  99, 100, 101 

M 

Maintaining  Powers  285, 286,287,291 


495 


496 


THE    MODERN    CLOCK, 


Pallets,  Drawing 116 

Pendulum  Brackets 32 

-       "  Mercurial 67,  71,  75 

"  Torsion  ....92,  93,  94,  95 

Oscillation  of  10, 14, 21 

"  Rieffler 50,75 

Perpetual  Calendar  Clocks.. 

354,  356,358 

"  Brocot 

....360,  362,   363,364.  366 

Pinion  Drill 251 

Pitch  Diameter  202, 218, 219, 220, 239 

Plate,  Jeweling .475,  476 

Posts - 480 

Precision  Clock  Room 453 


Q 


Quarter  Chiming  Snail  Trains 341 
Quail  and  Cuckoo  Train...322, 324 

Rack,  Division  of 335 


Regulator  Trains  465, 467, 479 

Rounding  Up  Wheels 220, 224 

s 

Secondary  Dials 4l6 

Self  Winding  Clocks.... 

—.400,  401,   404,  406,  408,  412 

Ship's  Bell  Train .314, 315, 316 

Slide  Gauge  Lathe 241 

"      Tools  243 

Snail,  Laying  Out ...337 

"      Striking  Trains 

333,342,345,  346 

Suspension  Springs 84 

Synchronizing  Clocks 412,415 

w 

Wheel  Cutting  Engine 255 

Wiring  Systems 386,388 

Wood  Rod  and  Lead  Bob 33 


Zinc  Bob  and  Wood  Rod^ 


.31 


INDEX. 


Addendum  202 

Air,  Pressure  of 20 

Aluminum,  Compensation 

with 48 

Anchor  Escapement 141 

Angular  Measurement,  Pecu- 
liarities of 102 

Apparent  Time 348 

Arbors,  Polishing  Steel —232 

Straightening  Bent  -.231 

Arc  of  Escapment 93,109, 

115,  127,  138, 145,  153,  164, 186,  469 
Armatures,  Adjustment  of  389,409 

Astronomical  Clocks 493 

••  Day 348 

Auxiliary  "Weights, 37 

Balance,  Vibrations  of 180 

Banking... ..90, 156, 160, 170, 176 

Barometric  Error 20 

Barrels—. 244,267,465,485 

"        Chiming 370 

Batteries 380 

"  Dating 392 

Grading .384 

Making... 383 

"  Position  of ..385 

"  Wiring,  Methods  of  385 

Beat,  to  put  a  Clock  in.. 89 

Bells .369 

•'     Ships  315 

Brocot's  Calendar 359 

"          Visible  Escapement 

127,128 

Bushing 476 


Cables,  Clock 269 

••        Lengths  of... 271 

Calculations  of  Weights 57 


Calendars 347 

Brocot's 359 

Gregorian ..349 

Julian 349 

"  Perpetual 353 

*'  Simple 350 

Carillons 372 

Case  Friction  -.. 448 

'*      Temperature 450 

Cases 446 

Gilding 459 

Marble 460 

to  Polish 461 

Polishing  ..  457 

"       Precision  Clock 447 

Regulator   463 

"       Restoring  old ..455 

Cement  for  Marble 460 

for  Dials 438 

Center  Distances 110,  200 

"         of  Gravity 18 

of  Oscillation 13 

Springs 96,294 

Chain  Drives 271 

Cheap  Clocks,  to  clean  - 187 

Chime  Barrels,  to  mark 371 

Chimes 339,370 

Cambridge 372 

Carillon 372 

Electric.-.: 420 

Tubular 374,422 

Circle,  Pitch 202 

Circular  Error 21 

Pitch 215 

Cleaning  Cheap  Clocks 187 

Clocks,  Astronomical 493 

Cuckoo 319,  321 

'•       Designing -8 

"       Four-hundred  day 91 


497 


498 


THE    MODERN    CLOCK. 


Clocks,  Glass  of.. -  4fi2 

Repeating ....332 

•'        Room 452 

Cock ._. .-..482 

Collets..- .-  234 

Compensated  Pendulum  Rocts  40 

Rod,  Flat .^1 

"  Rods,    Tubular. -48 

Compensation . 450 

Compensating  Pendulums.... 23 

Bracket  for 32 

Compensating  Pendulums, 
Principles  of  Construc- 
tion   27 

Compensating  Pendulums 

with  shot ._ - 36 

Compensating  Pendulums, 

Wood  Rod  and  Lead  Bob ....  32 
Compensation  Pendulums, 

Wood  Rod  and  Zinc  Bob. -28 
Compensation  Pendulums, 

Aluminum 48 

Cones,  Rusting  of 190 

Construction  of  Dials 426 

Contacts,  Dial 423,425 

Electric ...396 

Contrate  Wheel. ..- 171,  375 

Conversion,  Table  of 18 

Cords 2C8 

"      Lengths  of 270 

Count  Hook ..301,  304,  310 

*•      Wheel 301,304,315 

"  '*     Train 300 

Crown  Wheel 171 

Crutches 87,  472 

Cuckoo,  Adjustments  of 326 

Bellows 328 

"         Clock,  Names  of 

Parts 323 

"  Motion  Work 296 

Repairing .327 

Cutters  for  Clock  Trains 196 

Setting 197 

Cycloid ...21 

Cylinder    Clocks,   Examina- 

tion  of 171 

Cylinder,  End  Shake 170 

"             Propor- 
tion of 149 

Side  Shake 167 

•*  Teeth,  Shape  of... .183 


Cylinders,  Weight  of 37 

D 

Day,  Astronomical 348 

Sidereal... 318 

"        Solar 348 

Dedendum 202 

Denison  Escapment 150 

Depolarizers 3S1 

Depthing 200 

"         Tool ...477 

Designing  Clocks 8 

Detached  Lever  Escapement  184 

Dials,  Construction  of 426 

"       Contacts.- 423,425 

"       Enamel  for .431 

"       Phosphorescent ..437 

Repairing 432,438 

•'       Secondary 417 

to  Clean 436 

"        "    Silver 434 

"       Varnish  for... 438 

Distances,  Center ...200 

Drawings,  to  read 98 

Draw  of  Teeth 191 

Drill,  Pinion 249,251 

Drop... 1 107 

E 

Effect  of  Temperature 62 

Eight  Day  Trains 299 

Electric  Chimes .420 

"         Clocks 376 

"  "        Synchronizing 

400,413 

"  Contacts 396 

Elements,  Mechanical .98 

Enamel  for  Dials... 431 

End  Shake, of  Cylinder.. .170, 175 

End  Stones  .... 477 

Epicycloid 206 

Equation  of  Time ..365 

Error,  Barometric 20 

"       Circular 21 

"      Temperature 22 

Escape  Wheel,  Sizes  of  109, 

.-.133,  155, 164 
'•  "  To  make.- 

109, 120, 135, 138, 
150,155,162,161 


THE    MODERN    CLOCK. 


499 


Escapement,  Brocot's 127, 128 

Cylinder 163 

"  Denison 150 

"  Detached  Lever  184 

Drum 148 

Graham 109 

Gravity 150,161 

••  LePaute's  Pin 

Wheel 135 

Pin 185,193 

Recoil - lil 

"  TodrawGrahamll3 

"  Pin  Wheel  138 
"  Gravity -.152 
"  Western  Clock 

Mfg.  Co 193 

Examination  of  Cylinders — 171 
Expansion  of  Metals 22 

F 

Fan 308,326 

Fly  for  Gravity  Escapement--158 

Frames,  Making.-- 261 

Thickness  of 474 

Four-hundred  Day  Clocks 91 

Friction,  Disengaging..-. 203 

"  Engaging 203 

of  Teeth... 132 

"  Springs- 294 

G 

Gathering  Pallet 338,344 

Gilding 459 

Gong  Wires 369 

Graham  Escapement 109,467 

Gravity,  Center  of 18 

"        Escapement 150 

Gregorian  Calendar 349 

H 

Half  Hour  Striking  Work 

334,312,345 

Hammers ..367 

Hardening..  .198, 480, 482 

Springs .—368 

Tail 298,301 

Hands 439 

"      Proportions  of 440 

"     To  Balance 442 

•*     To  Blue 444 


Hour  Rack 335 

"     Snail - 296,334 

"     Strike 342 

'•     Wheel.-     96,  293,  2^r,.  325 

Ilypocycloid  Curves 206 


Iron,  Expansion  of 57 

Information,  Need  for 3 

Isochronism 469 


Jeweling-. 475,477 

Jewels,  Pallet 126 

Julian  Calendar 349 


Lantern  Pinions .-- 235 

Lathe,  Slide  Gauge—. 241,  li43,  246 

Laws  of  Pendulums .^..11 

Lead 22,32 

Leap  Year.. 349 

Length  of  Pivots.... ..199 

Lepaute's  Escapement 135 

Leverage  of  Wheels 99 

Lift- 106 

Lifting  Cam .-.301,331 

Piece ----331 

Planes 116 

Pins 186 

Lock 107 

Locking  Hook 301 

Losing  Time 192 

Lunation 365 

M 

Magnets,  Arrangement  of 

378,  386,  389,  395,  401,  406 

Mainsprings 272,  274, 277, 278, 

279,  280,281,282 

Breakage  of 281 

Buckled 277 

"  Cleaning 277 

Clock 288 

Coil   Friction... -277 

Fuzee 279 

"  Importance  of 

Cleaning 274 

Length  of 280 


500 


THE    MODERN    CLOCK. 


Mainsprings,  Loss  of  Power. ..274 
"  Maintaining 

Power.— 285,291 

Oiling 278 

"  Stop  Works 282 

Maintaining  Powers 285 

Mean  Apparent  Time 348 

Mean  Time ...348 

Measuring  Wheels 195 

Measurement,  Angular 102 

Mechanical  Elements 98 

Mercurial  Pendulums.— 53,  60,  09 
For  Tow- 
er Clocks  65 

Mercury.. 53,56,66,70 

Metals,  Expansion  of 22 

Weight    of 37 

Millimeters  Compared  with 

Inches 18 

Minute  Jumpers _..-..  417 

Wheels 96,293,296,325 

Month  Clocks 260 

♦•'     Sidereal 349 

"      Synodic 350 

Moon,  Phases  of 365 

••       Train.... 365 

Motion  Work 96,  293,  296, 325 

N 

Need  for  Information 3 

Numbers,  Conversion  of 201 

Nut,  Rating 42,50,66 

o 

Oiling  Cables - 269 

Oscillation,  Center  of 13 

Overbanking 90, 156, 160, 170, 176 


Pallet  Jewels 126 

Pallets..l06, 115, 121, 126, 130, 135, 
-139,  141, 144, 149, 153, 186, 193,  470 

Pallets,  To  make 119, 126 

Pendulum,  Isochronous 470 

Lengths,  Table  of 

10,16 

Rieffler 49,  75 

Rods 262 

"     Compensated  .40 

Comi)ensating 23 

Electric  Driven... .376 


Pendulum,  Laws  of 11 

Mercurial 53,60,69 

"  Sidereal 493 

"  Torsion. ...91 

Perpetual  Calendar E53 

Phases  of  the  Moon .365 

Pillars,  Making _ 240 

Pinion  Drill,  Atrtomalic--.249,  251 

Making 227,252 

"  "       Machine,  Auto- 

matic-.245, 247 

Canon 293,294.295 

Depthing 206,  210,  217 

"       Facing 233 

"       Hardening 229 

"       Lantern .235 

"       Tempering 230 

*'        To  Draw. 206 

Pin  Escapement -..    ..185.193 

"    Wheels 297,  301,  327 

"  •*      Escapement.. 135 

To... 
Draw  138 

Pitch,  Addendum 216 

"       Circle 202 

•'       Circular 215 

"       Diametral 216 

Pivots 488 

"     Length  of 199 

"     Proportions  of  167,173,199,474 

'*     Side  Shake ...199 

Planes,  Lifting 116 

Plates,  Clock 198 

"       Thickness  of 474 

Poising  Balance  Staffs...  189,190 

Polishing  Steel  Arbors 232 

Posts,  Clock ..478 

Power 264,  265,  266,  267 

"      Maintaining 285 

Putting  in  Beat 89 

R 

Rack,  Division  of 335 

Striking  Work 331 

Ratchet 288 

Rating  Nut 42,  50,  66 

With  Shot 90 

Reading  Drawings 98 

Repeating  Clocks 332 

Recoil  Escapement 141 

Regulation 79 

Regulator  Trains..- 492 


THE    MODERN    CLOCK. 


501 


Regulators,  Making 463 

Repairing  Dials 432,438 

Resistance  Spools 368 

Rieffler  Pendulum 49,75 

Rounding  Up 174,221,223 

"Rules  for 226 

Run 108 

Rusting  of  Cones 190 

S 

Screws,  Clock 483 

Secondary  Dials 417 

Self-winding  Clocks 376 

Ship  Bells,  Striking 313 

Shot,  Rating  with •.SO 

Sidereal  Day —  -348 

Month 349 

Pendulums - 4S3 

Year —.349 

Side  Shake,  Cylinder —167 

"     For  Pivots 199 

Silvering  Dials 434 

Simple  Calendar 350 

Sizes  of  Teeth —.211,213,237 

"      "   Wheels... COl 

Slide  Gauge  Lathe 241,243,244 

Snail......... '^96,  33') 

"    Division  of 337 

"    French  System 342 

••    Quarter  Striking  Work. ..339 

"    Striking  Work .330,340 

Solar  Day— - 348 

Sparking,  to  Prevent —  386 

Springs,  Center 294 

Clock 273,288,307 

"  Friction.. 294 

Hammer 368 

Main 272,273,274, 

.—277,  278,  279,  280,  282,  307 

Squares,  Milling...... -..261 

Standards,  Importance  of 26 

Star  Wheel 332,335 

Steel,  Expansion  of 57 

Stop  Works 282 

Straightening  Bent  Arbors — 231 
Striking  from  Center  Arbor. -.298 

To  Correct 306,307 

'•     ■     Trains.297, 308, 313, 323, 330 
"  "       Half  Hour... 

...298,  308,  313 
"  "       Setting  Up. - 

.-.-307,  310,  339 


Striking  Trains,  To  Calculate. 297 

Rack 331 

Work,  Repeating  ..  .332 

Snail 330,340 

Supports,  Pendulum — 86 

Suspension 81,  93 

"  Springs 82,93 

Synchronizing 400,413 

Synodic  Month 350 

T 

Table,  Lengths  of  Pendulum 

12,16,17,34,258 

"        of  Expansions 30 

"        "   Inches,  Millimeters 

and  French  Lines. .18 

"        "   Time  Trains 258, 

339,  340,492 

"         "    Weights  and  Metals.37 

Tangent 104 

Teeth,  Friction  of 132 

Shape  of  Cylinder 183 

"       Shapes  of.. 203 

Sizes  of 2.1,  213,237 

Temperature,  Effect  of..- 62 

Error 22 

Tempering 229 

Time,  Apparent 348 

"       Equation  of 365 

"       Losing.. 192 

Mean... 348 

To  Draw  Anchor  Escapement 

143,  145, 147 

Top  Weights 39 

Torsion  Pendulums 91 

Tower  Clock,  Cables .269 

"           "       Dials,  Sizes  of.. .426 
"           "        Gravity  Escape- 
ment for 150 

Hands ..442 

"  "        Maintaining 

Powers.. -285,  291 
Motion  Work--.-295 

"  "       Pendulums 65 

Stop  Works 2S7 

*'  "        Suspension 65 

t<       Time  Trains 258 

Trains 330 

Electric 389 

Regulator 492 

"      'Table  of 258 

"       To  Calculate— .257, 264, 297 


502 


THE    MODERN    CLOCK. 


Tropical  Year 3*8 

Tubular  Chimes 374,  422 

Turning  Tools 481 

Y 

Varnish  for  Dials 438 

•*         Remover .456 

Vibrations  of  Balance 180 

w 

Warning-. 306,312 

Pin 306,312 

Wheel 306,312 

Weight  Cords 268 

Weight  of  Lead,  Zinc  and 

Cast  Iron  Cylinders 37 

Weights 265,  319 

"         Auxiliary 37 

"         Calculations  of 27 

Top 39 


Wheel  Contrate 171,375 

Crown 171 

Hour 296 

Cutting 254 

Leverage  of 99 

Measuring 195 

Minute 96,  293,  296,  325 

Sizes  of 201,  490 

Stamping 256 

Star—-.-. 332,  335 

Stretching 226 

Wires,  Gong 369 


Y%ar , I 348 

"    Leap 349 

"    Sidereal ..349 

"    Tropical.. 348 

z 

Zinc 54 


.-^xC^t^-C--^- 


BIG  BEN  Is  the  first  and 
only  alarm  sold  exclu- 
sively to  jewelers.  He 
is  without  exception  the  finest 
sleepmeter  made  —  the  best 
looking,  the  best  built,  the 
best  running. 

Big  Ben  is  a  beautiful  thin 
model  alarm  clock  standing  7 
inches  tall  and  mounted  in  a 
reinforced  triple  plated  case. 
He  is  fitted  with  big  strong 
easy  winding  keys,  clean  cut 
heavy  hands  and  a  large  open 
winsome  dial,  distinctly  visible 
across  the  largest  room. 

Big  Ben  rings  just  when  you 


want  and  either  way  you  want, 
intermittently  for  fifteen  min- 
utes, continuously  for  ten, 
and  he  rings  with  a  jolly  full- 
tone  ring  that  will  arouse  the 
drowsiest  sleeper. 

Big  Ben  is  rigidly  inspected, 
six  days  factory  timed  and 
tested.  He  works  only  for 
jewelers  and  then  only  for 
certain  jew  elers  —  those  that 
agree  to  sell  him  for  not  less 
than  $2.50. 

We  pay  his  railroad  fare  on 
all  orders  for  a  dozen  or  more, 
we  brand  him  with  your  name 
in  lots  of  24. 


Height  7  inches.     Dial  4/4  inches.     Intermittent  or  Long:  Alarm. 
Dealers'  names  printed  free  on  dials  in  lots  of  24. 
Freight  allowed  on  orders  for  one  dozen  or  more.    - 


Western  Clock  Mfg.   Co< 


New  York 


La  Salle,  Illinois 


Chicago 


503 


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504 


SELF  WINDING  CLOCK  CO 

NEW  YORK 


Self  Winding  Synchronized  Clocks, 
Primary  and  Secondary  Clock  Systems, 

for 
Railroads,  Public  and  Office  Buildings, 
Hotels,  Universities,  Colleges, 
Schools  and  Private  Residences. 

Self  Winding  Program  Instruments, 
Jewelers'  Regulators, 
Bank  Clocks, 

Tower,  Post  and  Bracket  Clocks. 
Making  Clocks  to  Architects'  designs 
a  specialty. 


Hourly  signals  of  correction  from  the  U.  S. 
Observatory  at  Washington,  D.  C.  over  the 
lines  of  the  Western  Union  Telegraph  Co. 


505 


Tools,  Materials 
and  optical  Goods 


506 


In  1854 


Waltham  Watches 


awakened  Europe  to  the  fact  that 
the  American  method  of  manufac- 
turing produces  the  best  watches. 
Since  that  time  the  burden  of  proof 
has  been  successfully  carried  by 
17,000,000  WALTHAM  WATCHES 
all  representing  the  highest  stage  of 
the  watchmakers'  art. 


507 


Howard  Clocks 


Are  modern  in  •the  sense 
that  they  are  the  best 
timekeepers  in  the  world 
although  we  have  been 
making  them  since  1842, 
when  our  business  was 
established  by  Edward 
Howard.  W^e  guarantee 
satisfaction  and  respect- 
fully solicit  your  business. 


I!i£  £•  Howard  Clock  Co. 

BOSTON,  NEW  YORK  AND  CHICAGO 

Makers  of  Clocks  but  only  of  the  highest  grade  in  their 
respective  lines 


Jewelers'  regulators,  electric 
clocks,  house  and  office  clocks, 
locomotive  and  engine  room 
clocks,  marine  clocks,  pro- 
gramime  clocks,  post  or  side 
walk  clocks,  tower  clocks, 
watchman  clocks,  employes' 
time  recorders. 


508 


IqgerscMTenton 

The  Best  Seven  Jewel  Watch 

GUARANTEED 


r*5 


to 


[»15 


The  first  watch  guarantee 
ever  issued  was  that  placed  on 
the  cheapest  watch  ever  made 
—  the  Dollar  Watch  —  nine- 
teen years  ago. 

For  those  nineteen  years 
while  selling  nearly  nineteen 
million  Ingersoll  watches,  we 
have  been  asking:  "Why  are 
expenslue^je^weled  watches  not 
guaranteed?" 


The  Ingersoll-Trenton  is  the  first  and  only 
high  grade  7-iewel  watch  made  complete  and 
cased  in  one  factory ;  and  therefore,  the  only 
one  that  can  be  guaranteed  by  its  makers; 
others  are  assembled  from  movements  made  in 
one  factory  and  cases  from  another,  by  the 
dealer,  often  a  competent  jeweler,  but  often, 
too,  without  facilities  such  as  the  adjusting-  and 
timing  synems  existing  in  our  complete  -watch 
factory. 

The  "I-T"  has  all  features  of  the  most  re- 
cent, costly  watches,  which  secure  accuracy. 
"l-T"  gold-filled  cases  contain  gold  enough  to 
outlive  their  guarantees.  Sold  only  through 
responsible  jewelers,  who  buy  direct.  If  not  on 
sale  in  your  town  we  will  send,  prepaid  ex- 
press, on  receipt  of  price. 

INGERSOLL  WATCHES 

For  seventeen  years  there  has  been  but  one  standard  in  everj^day  watches;  "Ingersolls" 
have  popularized  the  very  use  of  watches.  One  friend  says,  "They  have  made  the  dollar 
famous."  They  have  never  been  so  worthy  of  their  great  reputation  as  today.  Fully  guaran- 
teed. They  include;  The  Dollar  Watch;  the  "Eclipse"  at  S1.50;  the  new  thin  model 
"Junior"  at  S2.00;  and  the  "Midget"  ladies'  size  at  S2.00.  Sold  by  60,000  dealers  orpost- 
paid  by  us. 

ROBERT  H.  INGERSOLL  &  BRO. 

New  York      Chicago         London         San  Francisco 


509 


THE  GREAT 
AMERICAN 
CATALOGUE 


Have  you  added  this  Salesman  to 
your  selling  force  ? 

Purchasing  Goods  from  the  Great 
American  Catalogue  insures  prestige 
and  the  confidence  your  customers 
will  bestow  upon  you  will  be  apparent 
in  increased  patronage. 

Our  Catalogue  meets  with  cordial 
approbation  of  old  stand-by  customers 
who  are  in  a  position  to  judge  of  the 
meritorious  results  obtained  through 
constant  use,  as  the  best  purchasing 
medium. 

Please  permit  us  to  send  you  a  copy. 


The  Oskamp-Nolting  Co. 

No.  411-413-415-417  ELM  ST, 
Cincinnati     ::     ::     ::     Ohio. 


510 


MOSELEY 


Made  Continuously 
for  over  30  years 


Imitated — but 
NEVER  EQUALED 


The  Standard  of  Excellence 

Nothing  is  overlooked  in  their  manufacture  and  no 
expense  is  spared  to  make  them  RIGHT.  The  Genuine 
Moseley  Lathe  of  to-day  is  the  result  of  years  of  painstak- 
ing, systematic  and  skilled  endeavor  to  satisfy  the  exact- 
ing requirements  of  the  most  critical  and  experienced 
workmen. 

Moseley  Chucks  are  of  the  best  quality,  and  are  made 
in  all  sizes;  covering  every  need  of  the  Watchmaker  and 
Repairer.  These  Chucks  and  Lathes  were  manufactured 
by  us  for  years  under  the  direct  supervision  of  CHAS.  S. 
MOSELEY,  the  inventor  of  the  "Split  Chuck"  and"  Draw- 
n-Spindle." 

Moseley  Lathes  and  Attachments,  with  plenty  of  Mose- 
ley Chucks  are  the  secret  of  rapid  and  accurate  work. 
They  increase  your  earning  power  by  enabling  you  to  do 
more  work  in  a  day.  As  an  investment  they  pay  big 
dividends. 

Write  your  JOBBER  for  the  NEW  MOSLEY 

CATALOG--INSTRUCTION.-REFERENCE  BOOK  No.  11 

"YOU  NEED  IT  EVERY  DAY." 


THERE'S  NO  LATHE  LIKE  THE  MOSELEY'^ 


511 


Clock  Tools  and  Clock  Materials 
form  an  important  and  extensive 
item  of  stock  in  our  Tool  and 
Material  Department,  at 

PRICES  THAT  DEFY  COMPETITION 


No.  2979.     Clock  Main  Spring  Winder. 
Nickel    plated,  $0.50 

In  Clock  Springs,  we  keep  the  best  polished  only; 
our  stock  consisting  of  all  die  most  desirable  widths 
on  the  market. 

If  you  do  not  possess  our  large  Tool  and  Material 
Catalogue,  kindly  send  us  your  business  card  and 
procure  one. 

We  can  save  you  time,  money  and  annoyance;  we 
are  anxious  to  make  your  acquaintance,  as  we  treat 
our  customers  with  the  utmost  courtesy  and  attention. 

A  trial  order  solicited. 


Otto  Young  &  Co. 

Wholesale  Jewelers  and  Importers  and  Jobbers 

Diamonds,  Watches,  Clocks,  Jewelry,  Tools, 

Materials  and  Optical  Goods. 

Hesrw^orth  Building,  Chicago 


512 


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BOSTON  COLLEGE  LIBRARY 

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If  you  cannot  find  what  you  want,  ask  the 
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,4' 


